The paper presents an evaluation of network services (CBR,. VBR and TCP over ... network configuration, called extended bottleneck topology. Comparing to ...
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Evaluation of ATM Service Quality In Future ATM Tactical Networks Andrzej BAK1, Andrzej BEBEN2, Wojciech BURAKOWSKI1,2, Zbigniew KOPERTOWSKI2, Marek LESNIEWICZ2, Piotr PYDA2. 1
Institute of Telecommunication, Warsaw University of Technology, 00-665 Warsaw, ul. Nowowiejska 15/19, 2 Military Communication Institute, 05-130 Zegrze
The paper presents an evaluation of network services (CBR, VBR and TCP over UBR) in the future ATM tactical network (e.g.[14]). The included numerical results refer to the tested network configuration, called extended bottleneck topology. Comparing to cable ATM network, the studied system takes into account wireless environment of tactical network. More precisely, the presence of transmission errors as well as radio access control protocol is assumed. Additionally, a comparison of ATM service quality between wireless and cable network is included.
practical experiments made in the Military Communication Institute ATM testbed [7]. The paper is organised as follows: the requirements about the QOS parameters referring to the particular ATM layer services (CBR, VBR and UBR) are presented in section 2. The numerical results are included in section 3. Finally, the section 4 summarises the paper. II.
I. INTRODUCTION The ATM technology is now being intensively introduced into the public and private telecommunication sectors because of its potential capability to support a variety of services, including multimedia. ATM market is growing faster every year, although there are many problems still not solved in a satisfactory way (e.g. traffic management, signalling, broadband services etc.). In the comparison to other telecommunication technologies [10] only ATM has ability to support whole range of applications with Quality of Service (QoS) guarantees. In 1996, the ATM Forum Wireless Working Group started work on the standards for the wireless ATM network (WATM). In order to adopt the ATM technology to a wireless environment, many problems should be solved because of high bit error rates in radio links and specific medium access protocols. The objective of the WATM network is to provide the same services as in the cable network (with similar QoS requirements). ATM was originally designed for fibre-optic transmission links characterised by extremely low error rate (10-12 or less). On the contrary, radio links are of rather high bit error rates, even 10-2 (depending on weather conditions, jamming etc.). The activities to adopt the ATM into the military tactical network environment were started a few years ago and still are in progress. The excellent example is the POST-2000 tactical network project. Results of the first experiments are very promising [11, 12, 13], however one can also find some difficulties, e.g. with efficient traffic management, error protection mechanisms, medium access protocols etc. The objective of this paper is to evaluate the quality of services in the ATM tactical network environment. The presented results were obtained using originally developed simulator working under OPNET simulation environment [9]. Simulation results were also partially verified by the
STUDIED NETWORK SERVICES
The ATM network services are precisely defined in [4] and they are1: CBR (Constant Bit Rate), VBR (Variable Bit Rate), ABR2 (Available Bit Rate), UBR (Unspecified Bit Rate). Numerical results presented in next section will illustrate the ability of the wireless ATM network to offer above services with required QoS parameters. Table 1 presents the values of QoS parameters required for mentioned above service categories [2]. TABLE 1
QOS PARAMETERS FOR SPECIFIC ATM SERVICES. CBR, rt-VBR VBR-nrt ABR CLR - cell loss ratio from 10-7 to from 10-9 to from 10-9 to 10-4 10-6 10-4 CDV - cell delay
