Fundamentals of ATM and Wireless ATM Networks

The emergence of B-ISDN has made the distinction between isochronous (voice and video) services and asynchronous (data) services to be less severe. ATM and B-ISDN are innovations in wired network technologies that could support voice, data and video services interchangeably [113]. For ATM-based systems, the conventional isochronous and asynchronous dichotomy has been replaced by a new regime to support: (a) constant bit rate (CBR), (b) real-time variable bit rate (rt-VBR), (c) non-real-time variable bit rate (nrt-VBR), (d) unspecified bit rate (UBR) and (e) available bit rate (ABR) services. Therefore, communication users requesting a virtual circuit can specify the type of service and the parameters in detail that further refine the demanded service.