无线宽带接入网中的ATM/AAL2

本文概要介绍了第三代移动接入网为采用ＡＴ斋 定义的新的适配层协议及其相应的信令协议。我们通过仿真计算表明面向时延敏感的低速业务而定义的ＡＡＬ２可以在满足业务质量要求的同时获得更高的资源利用率。与此同时,为了支持第三代移动通信网中的软切换和移动性,基于ＡＴＭ移动接入网要求快速建立和释放连接,这对ＡＡＬ２的信领协议提出了特殊的要求。     

基于ATM AAL-2的话音业务

电信网正朝着网络融合和业务综合的方向发展,要实现宽带网与现有窄带电信网络的有效融合,就要求宽带网能够很好地支持现有窄带网络或PSTN中的话音业务,实现话音的包传输与交换。ATM论坛最新通过的基于AAL-2承载话音业务的标准,为实现ATM宽带网与窄带网的融合提供了一个新的途径。本文根据ATM论坛基于AAL-2的话音中继标准,介绍AAL-2话音业务的原理,并给出基于AAL-2话音业务的网络融合方案。     

Tbit/s switching scheme for ATM/WDM networks

A new high capacity, reservation-based switch architecture for ATM/WDM networks is presented. The scheme is contention-free and highly flexible yielding a powerful solution for high-speed broadband packet-switched networks. Switching management and control are studied for data rates of up to 10 Gbit/s/port, providing and aggregated throughput of over 1 Tbit/s     

Protocols for ATM access networks

The development and standardization of ATM (asynchronous transfer mode) and signaling protocols for BISDN (broadband integrated services digital network) are considered. A view of both ATM and signaling protocols in which the key design guideline is service flexibility is presented. The approaches suggested are intended to create a service-independent broadband facility that is also sensitive to both service performance and network efficiency. Key issues are raised that will require serious consideration by standards groups, manufacturers, and service providers as BISDN moves toward production     

Polyhedral switching structures for ATM networks

The authors propose switching structures based on regular and non-regular polyhedra which ensure better QoS than the ATM switching networks known to date. The key idea of this solution is based on placing elementary switches on a sphere-shaped surface. Any set of adjacent switches forms a polygon, and the polygons in turn form a polyhedron     

Stochastic models for ATM switching networks

Models that take into account the fact that the switching speed may be appreciably greater than the speed at which some sources generate their respective cells are considered. The case is investigated where the cells making up individual bursts are spaced according to some prescribed probability distribution. It is shown that the switch performance is strongly dependent on the input parameters and it is demonstrated that analytical approaches provide useful alternatives to the lengthy simulation runs needed to evaluate probabilities of rare events, such as cell losses     

Applying ATM to mobile infrastructure networks

In response to the explosive increase in the number of mobile subscribers and the ever stronger demand for mobile multimedia services, the authors propose introducing the ATM technique for next-generation mobile network infrastructures in order to handle a high volume of traffic and develop multimedia communications. First, this article clarifies mobile-specific requirements for and advantages of applying ATM to mobile infrastructure networks. However, it is risky for network operators en bloc to replace the conventional STM-based infrastructure by ATM. Therefore, this article shows a smooth evolution path for the mobile network infrastructure to convert from conventional STM to ATM as mobile multimedia services mature. Even in future mobile networks, the main traffic may still be voice communications, whose bit rate is too low for efficient use of the radio frequency band. Applying ATM to such very-low-bit-rate mobile voice streams is inefficient due to the delay in filling out the payload of an ATM cell; this “packetization delay” degrades the quality of service. This problem can be solved by using a layered cell structure for the mobile ATM network. This cell structure enables the efficient transfer of voice signals ranging from very-low-bit-rate signals to high-speed multimedia signals with little delay. Standardization of this cell structure is progressing in ITU-T and the ATM Forum. Transmission efficiency is estimated by simulation     

Integrated cell and frame switching in ATM networks

Based on the per-VC queueing architecture, we propose a new technology to integrate cell and frame switching in asynchronous transfer mode (ATM) networks. We demonstrate that we can switch both fixed-length cells and variable-length frames inside the same switch at the same time. The insight is to recognize that we can store not only fixed-length cells, but also variable-length frames in each VC queue. The seamless integration of frame switching with cell switching will have a potential of merging frame relay with ATM     

Photonic access concentrator for ATM gigabit switching fabrics

In future broadband communication networks the interest for purely photonic switches is due to the bandwidth mismatch between optical transmission networks and electronic switching nodes. Photonic ATM switching fabrics mainly based on wavelength-switching stages are therefore being studied, to implement high capacity switches with also concentration, multiplexing and demultiplexing functions, using state-of-the-art photonic technology. The architecture of an ATM photonic access concentrator is described in this paper, illustrating the design and implementation of its basic subsystems, the traffic concentrator and the cell multiplexer. The design guidelines are outlined in detail referring to an example, where 128 user lines at 622 Mb/s are given access to 4 outlets at 2.488 Gb/s. The corresponding implementation, based on the systematic use of cell wavelength encoding, makes use either of well-known photonic components, such as Fabry-Perot filters, fiber delay lines, splitters and combiners, either of recently developed devices, like high-speed optical gates and tunable filters and lasers. Finally, the system feasibility is demonstrated presenting the results obtained on a reduced size and speed experimental setup of the cell multiplexer     

A novel switching architecture for ATM networks

It is known that the flexibility and capacity of asynchronous transfer mode (ATM) networks can meet the bandwidth requirements of multimedia applications. In ATM networks, switching is one of the major bottlenecks of end-to-end communication. We propose using a multiple partitionable circular bus network (MPCBN) as an ATM switch. Connection requests are first transformed into a graph where vertices and edges represent connection requests and conflicts among connection requests, respectively. We then use a graph traversal algorithm to select a maximal set of requests for execution in physically partitioned buses. An approach of using finite projective planes is then used to reduce the number of switch points from O(N²) to O(N √N), where N is the number of ports of a switch. A performance evaluation for both uniform and bursty data sources shows that the approach of using finite projective planes to reduce the number of switch points results in a small increase of cell loss probability     

Guaranteed quality-of-service wireless access to ATM networks

We study the problem of wireless access to asynchronous transfer modes (ATMs). We consider three classes of ATM sources: constant bit rate (CBR), variable bit rate (VBR), and available bit rate (ABR). We propose a polling scheme with nonpreemptive priority. Under such a scheme, we derive sufficient conditions such that all the CBR sources satisfy their jitter constraints and all the VBR sources satisfy their delay constraints. The remaining bandwidth is used by the ABR sources, for which we adapt a random access scheme proposed by Chen and Lee (1994). For this random access scheme, we derive the throughput-offer load characteristic, and thus the capacity. Based on this, we propose adaptive random access schemes that track the offer load to its optimal value. Our simulations show that our adaptive schemes maintain a high throughput with respect to the whole range of system load     

ATM technology for corporate networks

Asynchronous transfer mode (ATM) technology is discussed in relation to the requirements of corporate networking. An introduction to ATM switch architecture is presented. The various approaches to ATM switch design that have appeared in previously published literature are reviewed. A discussion is presented of some current issues facing the development of the ATM networks. It is argued that much simpler solutions to many of these issues may be adopted in the context of the corporate network than is permissible for the public broadband network     

A high-performance input access scheme for ATM multicast switching

In this paper, we propose an input access scheme for input-queued ATM multicast switches, achieving high system throughput, low packet delay and packet loss probability. Multicast and unicast packets of each input port are separately queued. Multicast queues take priority over the unicast queues, and both types of queues are fairly served in a cyclic-priority access discipline. In particular, each unicast queue is handled on a window-service basis, and each multicast packet is switched in a one-shot scheduling manner. To evaluate the performance of the access scheme, we propose an approximate analysis based on a simplified cyclic-priority model for anN×N finite-buffer multicast switch possessing Bernoulli multicast and unicast arrivals, with window-service (for unicasting) and one-shot scheduling (for multicasting) both taken into account. Finally, we show simulation results to demonstrate the accuracy of the approximate analysis and the superiority of the scheme over existing schemes with respect to normalized system throughput, mean packet delay, and packet loss probability.An earlier version of this paper appeared in IEEE ICC'96.     

Performance Analysis of the ATM Adaptation Layer 2 (AAL2)

In this paper, we analyze the performance of AAL2 multiplexer for a continuous time Markovian arrival process. AAL2 CPS (Common Part Sublayer) packets are multiplexed in the AAL2 multiplexing queue and transmitted in the transmission queue. This tandem structure suggests that the statistics of AAL2 CPS requires at least 2 dimensional state space. Furthermore, from a network-level point of view, cell multiplexing and de-multiplexing procedures are repeated at each AAL2 switching node. That requires simple analysis model. To solve this problem, we reduce the state space by showing that the output process of multiplexing queue can be modeled with the Coxian distribution. We propose a single dimension analysis model of the CPS transmission queue. When AAL2 convey both real and non real time short packets, QoS management is a problem. This is because the QoS of real time as well as non-real time packets is measured using different metrics – delay and cell loss ratio respectively. Most previous work is concentrated around delay performance due to the real time applications getting the primary attention. From the direct comparison of delay and CLR performance, we show that delay constraint is the dominant parameter in QoS of AAL2.     

基于ATM AAL2 Trunking 实现窄带网络与宽带网络互通

本文介绍了ATM AAL2 Trunking技术的由来及其原理,从窄带侧和宽带侧所支持的接口和协议,从窄带侧和宽带侧对信令的处理,从宽带侧对虚链路的管理等方面重点论述了窄带网络与宽带网络实现互通的方法。同时给出了窄带网络和宽带网络互通的实例,描绘了基于ATM AAL2Trunking实现窄带网络与宽带网络互通的发展前景。     

A signaling architecture for wireless ATM access networks

A multiservice wireless Asynchronous Transfer Mode (ATM) access system is considered from a signaling protocol viewpoint. In an attempt to generalize and extend results and experiences obtained from the specification, design, and implementation of fixed ATM‐based access networks, we extend the concept of the broadband V interface (referred to as VB) for application to wireless ATM access networks. The proposed architecture follows the signaling structure of Broadband ISDN (B‐ISDN) User–Network Interface (UNI), thus offering the possibility for integration of the wireless ATM access system into fixed B‐ISDN. It is shown that the use of the proposed access signaling architecture provides cost effective implementations without degrading the agreed Quality of Service (QoS), and simplifies call/connection and handover control. The evaluation of the proposed access signaling protocol structure yields results that fall within acceptable ATM signaling performance measures. A performance comparison of our approach with an alternative access signaling configuration is also carried out to quantify the relative gains. This revised version was published online in August 2006 with corrections to the Cover Date.     

Signaling stack design for wireless ATM access networks

One of the challenges in designing a wireless ATM network is to specify control functions capable of managing data and signaling connections of moving mobile terminals. The challenge is tough, due to the facts that such control functions neither exist in the current state-of-the-art wireless networks nor are included in the existing ATM specifications and implementations. This article describes the design principles of a wireless ATM signaling stack created in the WAND project. The article identifies some common problems and presents possible solutions to the problems. To justify the feasibility of the ideas presented, some details of a reference implementation, the Wireless ATM Network Demonstrator (WAND) signaling stack, are revealed     

Metropolitan area networks and ATM technology

Metropolitan area networks are evolving to fill the gap between local and wide area networks. The standards organization for such networks, IEEE Project 802.6, is defining a standard with unique advantages in scheduling and failure recovery. It is highly compatible with broadband ISDN and ATM switch technology. The resulting combination will be a seamless network embracing both customer buildings within metropolitan areas and world-wide interconnection.     

Full service optical access networks: ATM transport on passiveoptical networks

Multimedia communication has become the driving force for installing broadband systems in the public network. Different alternative solutions have been presented to realize a broadband interactive access network, such as installing optical fiber or upgrading the existing copper network with ADSL for twisted pair or hybrid fiber coax for CATV networks. Among these alternatives, optical fiber access networks are seen as the most future-safe solution. Especially, passive optical networks prove to be a cost-effective way to introduce fiber into the access network. This article presents ATM-based transport on passive optical networks, starting with a current implementation of an ATM-PON (APON) system that has already been installed for various trials. It further describes the evolution of APON systems to high-splitting, long-range PONs. The increase in both number of subscribers and distance range is discussed in combination with some specific technological issues such as upstream burst mode optical amplification. Special emphasis is placed on the work carried out within the scope of the ACTS PLANET project     

光网络中的光交换技术

在对光交换技术深入研究的基础上，对光网络中的关键器件，声光可调滤波器及光缓存器作了详细介绍，最后对光交换的发展前景作了展望。