Flow Control in Sampled Data Systems

Authors: Przemysław Ignaciuk Andrzej Bartoszewicz

Publish Date: 2013

Volume: , Issue: , Pages: 289-329

PDF Link

Abstract

For telecommunication operators the cost of running a particular algorithm is an important factor when deciding about its applicability in the supervised network Therefore the business point of view will generally favor such control strategies which allow for the explicit specification or at least estimation of the amount of the exchanged feedback information in relation to the transferred users’ data In consequence emitting feedback information carriers at regular time intervals which is assumed in traditional approaches for discretetime network modeling eg 2–5 is not cost efficient in the economical terms Instead one can send a feedback information carrier every N data packets and in this way place a direct limit on the extent of the transmitted management traffic with respect to the profit generating transmission of the users’ data Since this method relies neither on continuous feedback information availability nor on maintaining the synchronization of constant sampling period which is a serious challenge in multisource systems 1 it is more scalable and requires less control effort than the classical regulation schemes presented in the literature However sending a control unit every N data packets and not every T seconds means that after RTT the feedback information will be available for rate adaptation at the sources at irregular time instants Consequently in order to maintain adequate system performance the variable inputdependent sampling period should be explicitly accounted for in the design of flow control algorithm We will show however that the controllers developed for the system with constant discretization period in  Chaps 5 and  6 can be quite intuitively adapted for the case of variable sampling rate analyzed here Moreover we will demonstrate that provided that certain additional constraints are met the new strategies maintain the favorable properties of constantsamplingrate controllers In particular the proposed schemes will be shown to eliminate packet losses originating from unknown bandwidth variations and to ensure full bandwidth usage

Keywords: