Showing papers on "Broadband networks published in 1991"

Asynchronous Transfer Mode: Solution for Broadband ISDN

Abstract: A resource for the design or installation of ISDN that covers transfer mode, ATM switching, broadband transmission, broadband subscriber premises networks--including MANs (metropolitan area networks)--and broadband terminals. Explains and evaluates the advantages and disadvantages of alternative solutions for each topic.

Modeling and performance comparison of policing mechanisms for ATM networks

Abstract: Asynchronous transfer mode (ATM) networks, as proposed by CCITT as the solution for the future broadband ISDN, will provide high flexibility with respect to the varying bandwidth requirements of the different services. They will also support variable bit rates within a connection. The packetized information transfer, without flow control between the user and the network, in combination with the asynchronous multiplexing principle, results in a need to control the individual cell stream during the entire duration of the calls to ensure an acceptable quality of service for all coexisting calls sharing the same network resources. This kind of control will be provided by introducing a policing or usage parameter control function. Basic design objectives and requirements for such a function are described. These requirements serve as a basis for the comparison of some of the mechanisms proposed so far, namely the leaky bucket, the jumping window, the triggered jumping window, the moving window, and the exponentially weighted moving average mechanisms. >

Local area network characteristics, with implications for broadband network congestion management

Abstract: The authors examine the phenomenon of congestion to better understand the congestion management techniques that will be needed in high-speed, cell-based networks. The first step of this study is to use high time-resolution local area network (LAN) traffic data to explore the nature of LAN traffic variability. Then the data are used for a trace-driven simulation of a connectionless service that provides LAN interconnection. The simulation allows one to characterize what congestion might look like in a high-speed, cell-based network. When realistic data are applied to simple models of LAN interconnection, it is observed that during periods, congestion persists and losses can be significant; congestion losses cannot be avoided by modest increases in buffer capacity; consequences of misengineering can be serious; and, fortunately, most congested periods are preceded by signs of impending danger. >

Resource allocation for broadband networks

Abstract: The major benefit of a broadband integrated ATM (asynchronous transfer mode) network is flexible and efficient allocation of communications bandwidth for communications services. However, methods are needed for evaluating congestion for integrated traffic. The author suggests evaluating congestion at different levels, namely the packet level, the burst level, and the call level. Congestion is measured by the probabilities of packet blocking, burst blocking, and call blocking. He outlines the methodologies for comparing these blocking probabilities. The author uses the congestion measures for a multilayer bandwidth-allocation algorithm, emulating some function of virtual circuit setup, fast circuit switching, and fast packet switching at these levels. The analysis also sheds insight on traffic engineering issues such as appropriate link load, traffic integration, trunk group and switch sizing, and bandwidth reservation criteria for two bursty services. >

Multimedia synchronization protocols for broadband integrated services

Abstract: Protocols to provide synchronization of data elements with arbitrary temporal relationships of both stream and non-stream broadband traffic types are proposed. It is specified that the provision of a synchronization function be performed within a packet switched network, and, accordingly, a two-level communication architecture is presented. The lower level, called the network synchronization protocol (NSP), provides the ability to establish and maintain individual connections with specified synchronization characteristics. The upper level, the application synchronization protocol (ASP), supports an integrated synchronization service for multimedia applications. The ASP identifies the temporal relationships among an application's data objects and manages the synchronization of arriving data for playout. The proposed NSP and ASP are mapped to the session and application layers of the open-systems-interconnection (OSI) reference model, respectively. >

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

Abstract: The authors present a high-performance self-routing packet switch architecture, called Sunshine, that can support a wide range of services having diverse performance objectives and traffic characteristics. Sunshine is based on Batcher-banyan networks and achieves high performance by utilizing both internal and output queuing techniques within a single architecture. This queuing strategy results in an extremely robust and efficient architecture suitable for a wide range of services. An enhanced architecture allowing the bandwidth from an arbitrary set of transmission links to be aggregated into trunk groups to create high bandwidth pipes is also presented. Trunk groups appear as a single logical port on the switch and can be used to increase the efficiency of the switch in an extremely bursty environment or to increase the access bandwidth for selected high-bandwidth terminations. Simulation results are presented. >

A framing strategy for congestion management

Abstract: A congestion management strategy for integrated services packet networks that is robust with regard to transmission speed and network size is proposed. The strategy supports several classes of services with zero loss and different delay bounds as well as services without stringent loss and delay guarantees. Loss-free and bounded-delay transmission is accomplished by means of an admission policy which ensure smoothness of the traffic at the network edge, and by a service discipline called stop-and-go queuing, which maintains the traffic smoothness throughout the network. Both the admission policy and the stop-and-go queuing are based on a time framing concept described elsewhere by the author (IEEE Trans. Commun., vol.39, Dec.1991). This concept is further developed to incorporate several frame sizes into the strategy, thereby providing flexibility in meeting throughput and delay requirements of different applications. Stop-and-go queueing is realizable with minor modification to a first-in first-out (FIFO) queueing structure. >

Bandwidth and congestion management in accessing broadband ISDN networks

Abstract: This invention relates to a method and apparatus for controlling overload in a data network. The exemplary embodiment is a Broadband Integrated Services Digital Network (B-ISDN) in which data is transmitted within data cells included in a larger data frame using the Asynchronous Transfer Mode (ATM) protocol. In response to the network detecting overload, the network sends slow down messages to selected virtual channels to decrease their data rates. The network also acts to block or decrease resource allocations to transmission requests that are likely to overload the network.

Priority queueing strategies and buffer allocation protocols for traffic control at an ATM integrated broadband switching system

Abstract: The problem of furnishing an asynchronous transfer mode (ATM) based broadband-ISDN (B-ISDN) with two bearer services supporting different grades of transfer quality is addressed. The focus is on priority bandwidth and buffer management in the ATM communications nodes (switches, multiplexers or concentrators, and expanders) in the context of a multichannel network architecture. Detailed queueing analyses and simulations and results are provided to evaluate the differentiation between traffic classes that can be achieved by different strategies. The implementation complexity of the different schemes is discussed. Various priority queueing strategies characterized mainly by different degrees of resource sharing and a general system model for performance evaluation are introduced. Performance comparisons and design tradeoffs are addressed. >

Integrated broadband networks : an introduction to ATM-based networks

Abstract: Written by experts directly involved in the B-ISDN standards evolution, this book introduces the idea of integrated networks, and gives an overview of the current standardization situation. It discusses existing broadband networks based on the arising international standards, and explains how ATM is the basis for B-ISDN.

Congestion control and prevention in ATM networks

Abstract: Some of the congestion control methods commonly considered suitable for an ATM (asynchronous transfer mode) network are surveyed. Call-level control, which provides preventive control by regulating the admission of new calls into the network, is first discussed. The concept of equivalent bandwidth is defined, and the sharing of network information is discussed. Admission control schemes are described. Methods for cell-level control, which avoids short term congestion, are considered. Included are call admittance, bandwidth policing, and rate control, as well as priority schemes that provide multiple grades of service with ATM. >

A signaling protocol for complex multimedia services

Abstract: The author introduces a signaling protocol for user applications that invokes multimedia services provided by the EXPANSE research prototype, a broadband ISDN testbed A generic framework that flexibly accommodates a wide variety of services involving multiple parties with heterogeneous terminals is described The author describes the generic services supported, introduces the EXPANSE call model, discusses syntax and message flow procedures, and relates EXPANSE signaling to the ISDN signaling control part (ISCP) and long-term broadband ISDN signaling work currently under study by CCITT >

Control of resources in broadband networks with quality of service guarantees

Abstract: The design principles of resource control algorithms based on asynchronous time-sharing (ATS) are addressed, together with their interaction and cooperation in a wide area network environment, and a framework for evaluating the overall performance of the system is presented. The basic concepts of the ATS framework are presented, along with an overview of an architecture for joint scheduling and admission control. Scheduling mediates the low-level competition for service between cells of different classes; admission control regulates the acceptance or blocking of incoming traffic on a call-by-call basis. The performance of the scheduling algorithms is evaluated and the interaction between scheduling and admission control is quantified. A reference model for broadband networks is presented. >

Broadband CDMA for personal communications systems

Abstract: Multipath propagation in a broadband CDMA environment is described. A propagation model for broadband spread-spectrum signals is presented. Experimental results relating to the sharing of the band by fixed service microwave users and mobile personal communications network (PCN) users are discussed. Field tests indicate that PCN systems can provide high-quality communications when sharing the spectrum with fixed-service microwave systems in suburban and urban areas. >

An analysis of statistical multiplexing in an ATM transport network

Abstract: The traffic characteristics of an asynchronous transfer mode (ATM) network are analyzed by theoretical methods. A new method is proposed to express the burstiness of the cell arrival process. Both statistical multiplexing and statistical bandwidth allocation are quantitatively evaluated. When packetized video traffic and voice traffic are multiplexed, the number of multiplexable sources strongly depends on the peak bit rate of the multiplexed video sources, and statistical bandwidth allocation is ineffective without control. On the other hand, lowering the peak bit rate of video traffic effectively improves bandwidth utilization. >

On multicast path finding algorithms

Abstract: Three multicast path-finding algorithms for networks with directed links are designed and implemented: an optimal algorithm based on the dynamic programming technique, a heuristic algorithm with the assumption that all vertices have the multicast capability, and a heuristic algorithm for networks where some vertices do not have the multicast capability. Computation results show that the heuristic algorithms can find multicast paths whose costs are close to optimal and can operate with reasonable response time for large networks. Applications of these path-finding algorithms to set up multipoint connections for broadband multimedia multiparty services are discussed. >

Voice packetization and compression in broadband ATM networks

Abstract: Some methods of supporting voice in broadband ISDN, (B-ISDN) asynchronous transfer mode (ATM), including voice compression, are examined. Techniques for voice compression with variable-length packet format at DS1 transmission rate, e.g., wideband packet technology (WPT), have been successfully implemented utilizing embedded adaptive differential pulse code modulation (ADPCM) coding, digital speech interpolation (DSI), and block-dropping schemes. For supporting voice in B-ISDN, voice compression techniques are considered that are similar to those used in WPT but with different packetization and congestion control methods designed for the fixed-length ATM protocol at high speeds. Possible approaches for packetization and implementation of variable-bit-rate voice coding schemes are described. ADPCM and DSI for voice coding and compression and cell discarding (CD) for congestion control are considered. The advantages of voice compression and CD in broadband ATM networks are demonstrated in terms of transmission bandwidth savings and resiliency of the network during congestion. >

B-ISDN architecture and protocol

Abstract: The authors discuss the architecture and protocol for broadband ISDN (B-ISDN) based on the CCITT standards. The discussion attempts to address the general concept of B-ISDN architecture and protocol and, whenever possible, present alternatives and the rationale for decisions in the selection of the protocol. B-ISDN is presented as a network evolution, and the impact of the asynchronous transfer mode (ATM) on the network is described. The role of virtual channel and virtual path in B-ISDN is discussed. The B-ISDN protocol structure and lower layer functions comprising the physical, ATM, and adaptation layers are presented, and the tentative trends of signaling and traffic control for the B-ISDN are delineated. >

Integration of ATM call admission control and link capacity control by distributed neural networks

Abstract: An adaptive call admission control using neural networks was recently proposed for asynchronous transfer mode (ATM) communications networks. The author proposes adaptive link capacity control using neural networks. Neural networks are trained to estimate the call loss rate from link capacity and observed traffic, and link capacity assignment is optimized by a random optimization method according to the estimated call loss rate. The integration of adaptive call admission control and adaptive link capacity control yields an efficient ATM traffic control system suitable for multimedia communication services with unknown traffic characteristics. Computer simulation results using a simple network model are also given to evaluate the accuracy and efficiency of the proposed method. >

A layered broadband switching architecture with physical or virtual path configurations

Abstract: The authors describe a multilayer connection control architecture for broadband communications. A graph framework is introduced to describe network layers of network design, path configurations, dynamic call routing, burst switching, and asynchronous transfer mode (ATM) cell switching. These hierarchical layers of switching are performed at decreasing time scales, respectively. Switching at the higher layer is performed to reduce blocking at the next smaller time scale. A layered notion of equivalent bandwidth for satisfying layered grade-of-service parameters is introduced for making connections at these time scales. The authors then focus on the path configuration layer. Two path setup methods, namely, physical and virtual path setup, are described. Mathematical programs minimizing path bandwidth usage subject to meeting grade-of-service requirements are formulated for both methods. The relative merits of these methods are compared. In one example, physical path setup is shown to require roughly 50% more bandwidth than virtual path setup. >

Performance of a modified polling strategy for broadband wireless LANs in a harsh fading environment

Abstract: A radio-based communication network is considered in which a single, high-speed radio channel is shared by some plurality of small portable notebooks. Such a system has the potential to provide LAN-like service within buildings, allowing the portable notebooks to access the CPU and database resources of a wired network. In this harsh indoor fading environment, a base-station approach is used. A modified polling scheme for the indoor radio LAN channel is proposed. The base station regularly polls each remote, in response to which the remote either generates a keep alive packet or a request packet, allowing the base to fetch the requested information from the wired network and scheduling a reply to that remote. The efficiency of such a scheme is studied and the expected turn-around delay as a function of network loading is obtained. For a polling cycle of 20 ms and a network containing 10 or 50 users, for example, the maximum link efficiency is 97% and 87%, respectively. >

A protocol structure for high-speed communication over broadband ISDN

Abstract: 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. >

A telephone subscriber accommodation system in a broadband network

Abstract: On receiving voice data from a subscriber accommodated in a broadband network, a terminal adaptor separately puts the voice data in cells in 8-bit units every 125 μs separately, and transmits the cells by a remote switching unit in the broadband network to subscriber terminal equipment. The subscriber terminal equipment accommodates and processes each item of 8-bit data in 24 channels in the PCM format, puts in cells the PCM-formatted data in 24 channels, and sends the cells sequentially to a broadband network transmission line through the remote switching unit. On receiving the above described data in cells, an adaptor provided between the broadband network and an existing telephone network converts the data to the PCM transmission format, and sends them to the existing telephone network after adding a signaling bit to them.

Controlling congestion in B-ISDN/ATM: issues and strategies

Abstract: The high-level goals of a congestion control architecture are outlined. The controls are discussed in detail, focusing on the set of controls exercised by the network and the functionality needed at the network access and in the internal network elements. The end system controls are discussed only to the extent that they can benefit from the available network controls. The motivation for the suggested controls is discussed by describing their use for selected traffic types. Example traffic types and the use of some of the controls to support these traffic types in an integrated environment are examined. >

Controlling flow and avoiding congestion in broadband networks

Abstract: The basic design principles of flow control in asynchronous transfer mode (ATM) networks are examined. Network-level, call-level and cell-level flow control are covered. Dynamic bandwidth management and scheduling policies are discussed. >

Integrated broadband networks

Abstract: Evolution of network architectures advances in broadband switching modelling and performance analysis technologies characterizing traffic sources models for multiplexed traffic applications of modelling techniques congestion control and traffic integration.

The asymmetrical digital subscriber line (ADSL): a new transport technology for delivering wideband capabilities to the residence

Abstract: A brief overview of asymmetrical digital subscriber line (ADSL) technology is provided, describing important technology considerations, including noise impairments, spectral compatibility, and data-over-voice design challenges. Potential service applications utilizing the unique advantages of the ADSL are discussed, including advanced videotext, compressed video, and education applications. Network architecture and interface issues are addressed. Physical configurations at the customer premises and associated interfaces are discussed, along with a high-level view of possible network switching and control architectures. >

Distributed source control: a network access control for integrated broadband packet networks

Abstract: The authors propose a congestion control strategy called distributed source control (DSC), designed to address the integration of diverse traffic types in broadband packet networks. DSC is a rate-based network access control implemented at the asynchronous transfer mode (ATM) layer as a feedforward control, in conjunction with an adaptive end-to-end control between network edges. The authors examine the performance of high-speed data traffic such as large file transfers, still images, and document retrievals. The authors study DSC's integrability with real-time traffic such as voice and video. With the help of a simulation model of a broadband packet network (150 Mb/s), the authors quantify the improvement in network performance due to DSC. An analytic model for an access node under DSC is developed, and guidelines for sizing of buffers in the switch and for choosing the end-to-end window size are provided. >

System for integrated distribution of switched voice and television on coaxial cable

Abstract: A system for voice distribution amongst a plurality of telephone subscriber locations operating on a broadband cable network wherein RF transmitting and RF receiving channels for carrying voice and signalling information are established at the subscriber locations and coupled with the broad band network and a central switch is also coupled with the broadband network and enables each RF transmitting channel to be selectively coupled to any of the RF receiving channels.