Wireless ATM: Performance Evaluation of a DSA++ MAC Protocol with Fast Collision Resolution by a Probing Algorithm

In general, the users of wireless ATM terminalsrequest the same functionality and quality of service asusers of wired terminals. These user requirements can betransformed into the demand for building an ATM multiplexer around the air interfacewhich is characterized by a radio channel inside. Themain difference between this virtual ATM multiplexeraround the air interface and a fixed ATM multiplexer is the distribution of the multiplexingfunction between wireless terminals and the basestation. For the uplink this requires a frequentnotification of the ATM cell scheduler in the basestation about the status of the incoming buffers inside thewireless terminals. This paper focuses on differentmethods for transmitting capacity request messages (alsodesignated as reservation request) over theuplink.     

A Time Reuse Capture Access (TRCA) Protocol for PCS and Wireless ATM Applications

The Time Reuse Capture Access (TRCA) protocol isa medium access control protocol appropriate forpersonal communications and wireless AsynchronousTransfer Mode (ATM) applications. It is based on time reuse rather than frequency reuse. Frequencychannels are reused in every cell (frequency reuse one).Each FDMA channel has a TDMA frame structure. The numberof slots in the frame is equal to the time reuse factor and each slot is assigned to aspecific cell in the reuse cluster. Each mobile usertransmits in its assigned frequency channel and TDMAtime slot which corresponds to the cell it currently belongs. The protocol also exploits the powercapture phenomenon in which simultaneous transmissionsof users in adjacent cells may be successfully received.Two possible applications of the proposed TRCA protocol are considered in this paper. In thefirst application, TRCA is used for random packet accessin wireless personal communication. Users transmit theirpackets using the assigned and non-assigned time slots to take advantage of the effect ofcapture and non-uniform traffic loads. The portion oftransmissions that takes place in each time slot iscontrolled so that the overall throughput is maximized. In the second application, TRCA is used forreliable transmission of ATM cell over a wirelesschannel. The proposed protocol allows the transmissionof continuous bit rate (CBR) ATM cells over a wireless link so that bit error rate (BER) and delayrequirements are met. Transmissions take place in theassigned time slots but the non-assigned time slots canbe used for re-transmission if the previous transmission was unsuccessful.     

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     

Wireless ATM LAN with and without infrastructure

We consider wireless ATM concepts for small LANs, especially for SOHO and future consumer applications. We describe a wireless ATM LAN framework architecture that supports wireless ATM communications in environments with and without fixed ATM infrastructure. For the configuration with an ATM infrastructure, a distributed ATM switched backbone is proposed, which enables a smart ATM switching element to be embedded in every wireless and fixed access point. For bandwidth efficiency and ease of operation (place-and-play), we also propose an ad hoc wireless ATM LAN concept based on the same 5 GHz wireless ATM air interface as is currently under standardization in the ETSI/BRAN and ATM Forum. Unlike CSMA-based ad hoc systems such as HIPERLAN and IEEE802.11, our ad hoc wireless ATM system makes QoS management feasible in an infrastructureless environment by using resource reservation and scheduled medium access protocol. Since cost scalability is essential throughout our system design, we consider forwarding between ad hoc subnets and interworking with the fixed network as important but optional features     

基于ATM的无线宽带网络

本文首先介绍了无线宽带网络的技术背景和空中接口,然后讨论了无线宽带通信的核心技术－无线ＡＴＭ的基本原理,如网体系结构、信元格式、协议栈,以及关键技术等,最后给出了现有的无线宽带网络的实验系统和它的标准化进程。     

A New Digital Sense Multiple Access (DSMA) Protocol for High-Speed Wireless Networks

In this paper, we propose a new digital sensemultiple access with delayed transmission (DSMA/DT)protocol for reverse channel in high-speed wirelessnetworks. The new protocol is motivated by theobservation that the existing DSMA protocol does not yieldsatisfactory throughput for long round-trip propagationand processing delay, which occurs in outdoor high-speedenvironments or when the receiver hardware requires long signal processing time. The newDSMA/DT protocol is intended to reduce the performanceimpacts of the round-trip delay. Look-ahead busy/idleflag, seizure queueing, and reserved time slots are also devised for the new protocol. Whilerequiring at most two additional status bits on theforward channel and no additional hardware capability,these features further enhance the protocol performance and enable constant-bit-rate service withlittle added complexity in control. The channelthroughput of the DSMA/DT protocol and the optionalfeatures are analyzed. Closed-form expressions for thethroughput are obtained. For non-negligible round-tripdelay relative to packet transmission time, ournumerical results show that the new protocol improvesthe throughput by as much as 60% when compared to theexisting DSMA protocol. For superior performance andsimplicity, the DSMA/DT protocol will be appropriate foruse in high-speed wireless networks.     

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.     

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     

Designing a practical ATM LAN

The adaptor cards and driver software for workstations and local asynchronous transfer mode (ATM) switches and switch control software used in an ATM local area network (LAN) system are discussed. It is shown that the ATM hardware and software components together provide services that are essential for ATM to be considered a realistic alternative to current shared-media LANs. These services include: completely transparent support for the TCP/IP protocol suite, an application programming interface for full access to the underlying ATM capabilities, support for AAL5, AAL3/4, and the null AAL, both connection-oriented and connectionless service, dynamic connection establishment or switched virtual circuits, resource reservation of guaranteed bandwidth and quality of service, full-bandwidth multicast and broadcast, virtual path and channel routing among multiple switches, automatic configuration and failure recovery, dynamic address assignment and internetwork address resolution, and network management via the simple network management protocol (SNMP)     

ATM基本技术及其在公用网应用的主要难点

ＡＴＭ技术已被公认为实现宽带综合业务数字网（Ｂ－ＩＳＤＮ）的关键技术。本文将介绍ＡＴＭ技术的基本原理－ＡＴＭ概念，ＡＴＭ协议的分层结构，ＡＴＭ网络和接口，ＡＴＭ传输与复用技术，ＡＴＭ的交换技术，ＡＴＭ的信令方式，ＡＴＭ网络管理和管制以及ＡＴＭ技术在公用网应用中的主要难点。