Guest Editorial: Switching for Broadband Communications


T HE papers in this issue cover a broad spectrum of switching technology areas, in addition to some services and exploratory network architectures. However, much of the demand for broadband switches will be stimulated by the Broadband Integrated Services Digital Network (BISDN) currently under discussion in the Consultative Committee on International Telephony and Telegraphy (CCITT). Indeed, this network is viewed as the “communications umbrella” which will stimulate the need for switches, capable of handling data rates well in excess of 64 kbit/s, the limit of today’s ISDN switches. To provide a broader network perspective for assessing the papers, we begin this Editorial with a review of recent BISDN standards developments and BISDN network architectures. The primary triggers for evolving toward the BISDN include a demand for new high bit-rate services, and a potential reduction in the costs of supporting current services on the telephone network. These needs are made possible by the availability of high speed semiconductor and lightwave technologies and by the availability of advanced communication techniques. Table I shows the range of approximate bit rates required for various communication services. Three classes are roughly identified. Services within the “low speed” class are within the capabilities of the “narrowband” (i.e., the 64 kbit/s) ISDN recently defined by CCITT. However, services in the medium speed class are outside these capabilities, and are currently handled via private point-to-point or “channel switched” networks. It is expected that the BISDN will cost-effectively support switched connectivity for these low and medium speed services as well as selected services from the high speed class which have bit rates ranging upward to about 150 Mbit/s. It is interesting to note that image communications for high resolution (1-16 million pixels) interactive graphics/ video terminals may be one of the more demanding on the future broadband network. For example, if it is assumed that 24 bits per pixel are needed to provide color and gray scaling, a single screen may represent 24-384 Mbit. Thus, if an application such as the browsing of still images requires the update of a screen in $ s to minimize operator waiting time, then a transmission bit rate of 48-768 Mbits/s may be required. Table 11 shows trends in the improvement of basic information technologies over the past decade. These trends show, for example, that the capacity of lightwave systems measured in terms of bandwidth-distance product (information flow over a repeaterless span length) improves by TABLE I ROUGH BIT RATE FOR VARIOUS SERVICES

DOI: 10.1109/JSAC.1987.1146656

Cite this paper

@article{White1987GuestES, title={Guest Editorial: Switching for Broadband Communications}, author={Patrick E. White and Joseph Y. Hui and Maurizio Decina and Reigo Yatsuboshi}, journal={IEEE Journal on Selected Areas in Communications}, year={1987}, volume={5}, pages={1217-1221} }