Multicast forwarding over ATM: Native approaches

Multicasting is growing in importance as new multimedia applications are devised. Throughout this article, multicasting is understood as the efficient multipoint-to-multipoint transmission of information (in terms of network resource consumption) between the members of a group. Most multicast services have been designed up to now to work over connectionless environments. The approach adopted by connection-oriented networks has been to try to imitate these connectionless multicast schemes with the aim of supporting IP multicast or network-layer broadcast. However, these solutions present drawbacks in terms of delay or signaling overhead. The goal of native ATM multicasting is to provide multicast communications support by taking into account the characteristics of ATM. Therefore, the design philosophy of multicast must be rethought by making it more suitable for connection-oriented networks. Native ATM multicasting is based on mechanisms implemented at the switches to allow the correct ATM-layer multicast forwarding of information. These mechanisms seek to avoid the delay and signaling problems of current solutions, e.g., LAN emulation and IP multicast over ATM. This article provides a survey of the literature on the strategies that offer multicast communications in ATM environments, with special stress on native ATM multicast forwarding mechanisms. Other aspects, such as signaling, quality of service, traffic control, and routing, are not addressed in detail in this article.     

Virtual tree‐based multicast routing with a distributed numbering algorithm for WM‐ATM handover

The flexibility offered by the ATM transport mechanism and its potential capabilities, together with its compatibility with the B‐ISDN, makes ATM the prime candidate for the support of multimedia services over the wireless medium. However, technical issues remain to be resolved in relation to the feasibility of ATM for the support of mobility over the radio interface. This paper examines network issues in supporting handover in a wireless ATM network. In particular, analysis has been performed for a virtual tree-based network architecture. Results have shown that by using multicast transmission and by using a distributed numbering algorithm, the potential problems of cell-loss and cell-duplication have been eliminated. This revised version was published online in June 2006 with corrections to the Cover Date.     

Emerging wireless broadband networks

The rapid evolution of mobile wireless access networks toward multimedia support with QoS provision forces the development of advanced wireless broadband systems with high reliability and high data rate. To achieve this goal, new system design concepts with increased system capacity will be required. In that context, ATM is becoming a major infrastructure, receiving a lot of attention for telecommunication systems since ATM networks can most effectively support wireless access systems. Wireless ATM systems have low transmission cost, flexible functionality, mobile ATM protocol, and radio access layer protocols. This article overviews the various wireless broadband systems studied at 5, 19.37, 40, and 60 GHz by European Union funded projects within the ACTS program. Moreover, related standardization activities and network evolution are also addressed     

WATMnet: a prototype wireless ATM system for multimedia personalcommunication

A prototype microcellular wireless asynchronous transfer mode network (WATMnet) capable of providing integrated multimedia communication services to mobile terminals is described in this paper. The experimental system's hardware consists of laptop computers (NEC Versa-M) with WATMnet interface cards, multiple VME/i960 processor-based WATMnet base stations, and a mobility-enhanced local-area ATM switch. The prototype wireless network interface cards operate at peak bit-rates up to 8 Mb/s, using low-power 2.4 GHz industrial, scientific, and medical (ISM)-band modems. Wireless network protocols at the portable terminal and base station interfaces support available bit rate (ABR), variable bit rate (VBR), and constant bit rate (CBR) transport services compatible with ATM using a dynamic time-division multiple-access/time-division duplex (TDMA/TDD) MAC protocol for channel sharing and data link control (DLC) protocol for error recovery. A custom wireless control protocol is also implemented between the portable and base units for support of radio link related functions such as user registration and handoff. All network entities including the portable, base and switch use a mobility-enhanced version of ATM (“Q.2931+”) signaling for switched virtual circuit (SVC) connection control functions, including handoff. In the first stage of the prototype, the application-level API is TCP/UP over ATM ABR service class using AAL5. Early experiments with the WATMnet prototype have been conducted to validate major protocol and software aspects, including DLC, wireless control, and mobility signaling for handoff, Selected network-based multimedia/video applications requiring moderate bit-rates (~0.5-1 Mb/s) in the ABR mode have been successfully demonstrated on the laptop PC     

IP multicasting over ATM networks

The Internet protocol (IP) multicast model involves a combination of intrasubnet and intersubnet multicast mechanisms. Technologies supporting a given subnet are expected to have native mechanisms for supporting intrasubnet forwarding of packets sent to multicast destinations. Multicast routers attach to subnets and provide intersubnet forwarding of multicast packets, using interdomain multicast routing protocols developed by the Internet Engineering Task Force (IETF). Unfortunately, ATM networks based on UNI 3.0 or UNI 3.1 signaling service do not provide the native multicast support expected by IP. This has led the IETF to develop the “MARS model”-a fairly complex mechanism for emulating intrasubnet multicast support required when running IPs over ATMs. This paper takes a high level look at the IP multicast service, examines the limitations of the ATM point-to-multipoint virtual channel service, and describes the major architectural points of the MARS model     

Wireless ATM networks: technology status and future directions

The concept of “wireless ATM” (WATM), first proposed in 1992, is now being actively considered as a potential framework for new-generation wireless communication networks capable of supporting integrated, quality-of service (QoS) based multimedia services. In this review paper, we outline the technological rationale for wireless ATM, present a system-level architecture, and discuss key design issues for both mobile ATM switching infrastructure and radio access subsystems. The WATM radio access layer issues covered in this paper include: spectrum allocation; spectrum etiquette; modem technology; and medium access/data link control (MAC/DLC) protocols. Mobile ATM aspects such as ATM signaling extensions for handoff control, location management, and mobile QoS control are discussed. A summary of current wireless/mobile ATM technology development and standardization status is given, including an outline of our WATMnet prototype. The paper concludes with a discussion of future directions for wireless ATM technology such as Internet protocol (IP) integration and mobile multimedia terminals/applications     

Performance analysis of cache strategy for signaling traffic management in a wireless ATM network

In a wireless ATM network for mobile multimedia services, conventional signaling protocols generate heavy traffic because the signaling load must be handled in a HLR (Home Location Register). This centralized structure of the wireless ATM network causes critical connection setup delays. Thus, distributed processing based on a reduction of the connection setup delays is needed in wireless ATM networks. A cache strategy for call delivery with cache updates of registration based on ATM multicasting is introduced with a comparison of the cost of cache scheme with the cost of a conventional scheme. Results show that the cache scheme has better performance than conventional methods when portable mobility is low with large traffic density. This revised version was published online in July 2006 with corrections to the Cover Date.     

Scalable QoS-based IP multicast over label-switching wireless ATMnetworks

A Mobile IP multicast prototype that integrates a label-switching wireless asynchronous transfer mode, the mobile core-based multicast architecture, and an Internet multicast infrastructure is presented. MCOM creates multiple core-based layer 2 multicast trees that are independently established in member networks. They are interconnected via the Internet using layer 3 multicast routing. Gateways on the border of the Internet and wireless ATM networks convert ATM multicast traffic to suitable IP packets as well as converting from IP packets to ATM cells for MCOM. To solve the cell interleaving problem that results, ATM block transfer/immediate transmission capability is reasonably modified. Additionally, class-based block buffer management for ATM multicast connections is built into wireless ATM switches for soft quality of service control. Dynamic group management, multicast channel rerouting, and reliable multicasting are also studied in relation to existing Internet protocols like Mobile IP, Internet group management protocols, and multicast routing protocols     

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access     

FUTURE MULTIMEDIA COMMUNICATIONS VIA SATELLITE

We are now moving into an era when conventional speech service will expand to full multimedia service offerings. This paper looks at ways in which satellite systems could provide such services in both the mobile as well as the fixed bands and the integration and inter-operability of such systems. Provision of multimedia services by ATM to integrate with an ATM core network is taken as the basis of the future network. Some of the constraints and difficulties of provision of ATM over satellite are discussed as well as some potential solutions for the ATM wireless protocols and network architectures which potentially could provide such services. Finally, some suggestions of how new orbit constellations could help meet these requirements are given. © 1996 by John Wiley & Sons, Ltd.     

A signaling and control architecture for mobility support in wireless ATM networks

This paper presents a signaling and control architecture for mobility support in a wireless ATM network that provides integrated broadband services to mobile terminals. A system level protocol architecture for a wireless ATM network is outlined. The proposed protocol stack incorporates new wireless link MAC, DLC and wireless control sublayers, together with appropriate mobility extensions to the existing ATM network control layer. Wireless control and ATM signaling capabilities required for mobility support are discussed, and preliminary solutions are given for selected major functions. Potential extensions to standard Q.2931 ATM signaling are proposed to support handoff and service parameter/QoS renegotiation required for mobility. An associated wireless control protocol for supporting terminal migration, resource allocation, and handoff is discussed. Preliminary experimental results are given which validate the proposed handoff control protocol on an ATM network testbed.     

PCS mobility support over fixed ATM networks

As broadband multimedia services and wireless services become popular, there is growing interest in the industry to support ATM over a wireless link, and wireless access to fixed ATM networks. We focus on the internetworking of PCS and ATM networks, in which the air interface remains one of the PCS standards and the backbone is an ATM network with mobility support. It is desirable to minimize the impact of the internetworking and mobility support on the existing/emerging PCS and ATM specifications. A network architecture, a protocol reference model, and signaling protocols for PCS mobility support over fixed ATM networks are described. They are compared against other implementation alternatives and the trade-offs are discussed. Some performance results of the proposed architecture are also presented     

Cross-Layer Modeling for QoS-Driven Multimedia Multicast/Broadcast over Fading Channels in [Advances in Mobile Multimedia]

In this article we propose a cross-layer design model for multimedia multicast/broadcast services to efficiently support the diverse quality of service requirements over mobile wireless networks. Specifically, we aim at achieving high system throughput for multimedia multicast/broadcast while satisfying QoS requirements from different protocol layers. First, at the physical layer, we propose a dynamic rate adaptation scheme to optimize the average throughput subject to the loss rate QoS constraint specified from the upper-layer protocol users. We investigate scenarios with either independent and identically distributed (i.i.d.) or non-i.i.d. fading channels connecting to different multicast receivers. Then, applying the effective capacity theory at the data link layer, we study the impact of the delay QoS requirement (i.e., QoS exponent) on the multimedia data rate of mobile multicast/broadcast that our proposed scheme can support. Also presented are simulation results which show the trade-off among different QoS metrics and the performance superiority of our proposed scheme as compared to the other existing schemes.     

Mobility management and control protocol for wireless ATM networks

The introduction of wireless ATM (WATM) in customer premises network environments necessitates the design of mobility protocols, since the existing versions of B-ISDN signaling do not support terminal mobility. Such protocols can be deployed either as extensions to the standard signaling capabilities, or as individual solutions that have little or no impact on existing infrastructures (switches, signaling software, etc.). A WATM architecture that adopts the latter approach is presented. After a discussion of the problems encountered in the integration of wireless networking and B-ISDN ATM technologies, a mobility management and control (MMC) protocol is proposed. Finally, in the framework of the proposed MMC protocol, algorithms for implementing mobility procedures (handover and registration) are described     

控制接入ATM网的突发话音

ＡＴＭ网在同一条连接上能支持多媒体业务,各种媒体的速率、突发度参数和它们之间的相位关系都不同。要保证各种业务的服务质量（ＱＯＳ）,需要引入流量控制算法。本文介绍用于用户网络接口（ＵＮＩ）上的流量控制算法。     

Hardware-software architecture of the SWAN Wireless ATM network

The SWAN (Seamless Wireless ATM Network) system provides end-to-end ATM connectivity to mobile end-points equipped with RF transceivers for wireless access. Users carrying laptops and multimedia terminals can seamlessly access multimedia data over a backbone wired network while roaming among room-sized cells that are equipped with basestations. The research focus on how to make ATM mobile and wireless distinguishes SWAN from present day mobile-IP based wireless LANs. This paper describes the design and implementation of the ATM-based wireless last-hop, the primary components of which are the air-interface control, the medium access control, and the low-level ATM transport and signalling.The design is made interesting by its interplay with ATM; in particular, by the need to meaningfully extend over the wireless last-hop the service quality guarantees made by the higher level ATM layers. The implementation, on the other hand, is an example of hardware-software co-design and partitioning. A key component of the wireless hop implementation is a custom designed reconfigurable wireless adapter card called FAWN (Flexible Adapter for Wireless Networking) which is used at the mobiles as well as at the basestations. The functionality is partitioned three-way amongst dedicated reconfigurable hardware on FAWN, embedded firmware on FAWN, and device driver software on a host processor. Using an off-the-shelf 625 Kbps per channel radio, several of which can be supported by a single FAWN adapter to provide multiple channels, per-channel unidirectional TCP data throughput of 227 Kbps (or, 454 Kbps bidirectional) and per-channel unidirectional native ATM data throughput of 210 Kbps (or, 420 Kbps bidirectional) have been obtained.     

Wireless video applications in 3G and beyond

This article surveys wireless video applications that have been commercialized recently or are expected to go to market in 3G (and beyond) mobile networks, mainly covering error control technologies in view of "wireless video." We introduce several related 3GPP standards including circuit-switched multimedia telephony, end-to-end packet-switched streaming, multimedia messaging service, and multimedia broadcast /multimedia service. We also review the supporting technologies for those four applications. The article concludes with a discussion of error control and rate control adaptability to network QoS variation, which is distinct from wired networks and critical to wireless networks. With respect to MBMS, we point out that required cell transmission power is crucial when realizing meaningful multicast coverage, and suggest a system that integrates different unicast and multicast networks, application-layer data repair, and transmission scheduling.     

Charging for ATM services

Advances in analog and digital telecommunications technology have provided us with a wide range of telecommunications networks since the invention of the analog telephony network by Bell in 1876, such as wireless and wired CATV networks, local, metropolitan, and wide area networks, and the Internet; and a range of protocols to go with these networks, such as Internet Protocol or ATM. Charging for services delivered across these networks has always been an issue of major concern to providers and users of telecommunications services. The ability to charge accurately and efficiently for a service is directly related to the potential quality, value, flexibility, and customer care available to the customer, and, equally important, provides a means of survival, growth, and profitability to the provider. ATM is becoming a significant carrier of telecommunications services because its technology can accommodate a wide variety of services such as multimedia on demand, voice services, or videoconferencing, demanded by today's rapidly changing market. While there are many schemes in use for the charging of mobile and fixed telephony, the area of Internet charging and, in particular, ATM charging is relatively uncharted to date. In this article we address the challenge of developing methods of charging for ATM services, and show solutions in the form of technical and commercial recommendations and a practical implementation of these recommendations     

End to end QoS provisioning multimedia wireless/mobile networksusing an adaptive framework

This article presents a framework for multimedia networking in a wireless and mobile environment. We consider both multimedia application needs as well as networking requirements, and try to bridge these paradigms using an adaptive framework. Central to this framework is the concept of representing a multimedia connection in terms of multiple substreams each with their own specified QoS requirement and making network elements (switching and access points), services, and protocols (signaling, control, routing) aware of the QoS requirements of such substreams. As resource availability in the wireless and mobile network fluctuates, the network selects and schedules substreams in order to present the information content with an acceptable quality at a receiver (or each receiver in case of multicast connections). This is done while achieving a reasonable utilization efficiency of network resources and sharing them in a fair manner