On Dynamic Capacity Management in Voice/frame Relaying Networks

We consider call admission and capacity management in a dynamically recon gurable network that carries a multitude of tra cs. Our approach is a heuristic capacity assignment algorithm designed to maximise an arbitrary pro t function. The algorithm is based on the concept of equivalent circuits, i.e. a given relationship between transmission capacities and call handling capabilities expressed as e ective numbers of circuits. Such relationships are examined for the two tra cs of our application, voice and frame relaying. Methods and results are independent of the transfer mode used. 1 Statistical Multiplexing of Voice/Frame Relaying 1.1 Preliminaries Statistical multiplexing has become an increasingly complex issue with the integration of new services into telecommunications networks. Traditionally, information sources such as voice have been considered \smooth" which means that they produce information at an even, xed rate. Most new services, such as data carried over frame relaying [13, 28, 29, 38, 39, 40], are, however, the opposite of smooth, namely \bursty". It is well known that statistical multiplexing of bursty sources poses particular problems as compared to non-bursty sources. The approach taken here is a layered view of statistical multiplexing, as in e.g. [15, 26, 27, 42] and many others. We distinguish between two levels of multiplexing: Subscriber multiplexing: Statistical multiplexing of subscribers means exploiting the fact not all subscribers are likely to use their equipment at the same time. Connection multiplexing: Statistical multiplexing of connections takes advantage of the fact not all bursty connections are likely to transmit information at the same time. Statistical gain through multiplexing is always achieved at a certain cost: Multiplexing subscribers will cause rejection of some call attempts and multiplexing connections will result in some information being lost. It is the task of network engineering and network management to supply su cient capacity and to maintain reasonable call admission policies so that acceptable loss performance is achieved at both levels respectively. 1.2 Service Classes It is often assumed that a call can be classi ed as belonging to a certain class according to the characteristics of its capacity requirements. Table 1, extracted from [11], gives On leave from Department of Communication Systems, Lund Institute of Technology, Lund, Sweden.