Authors: Yukinobu Fukushima Wenjie Chen Tokumi Yokohira
Publish Date: 2015/05/13
Volume: 30, Issue: 2, Pages: 178-189
Abstract
Light trail networks have been proposed as an extension of lightpath networks in order to enable subwavelength bandwidth allocation in WDM networks The networks need a medium access control MAC method to avoid collisions of data transmissions We have proposed a MAC method which adopts a tokenpassing mechanism The method splits one trail into two trails one upstream trail and one downstream trail and permits independent data transmissions on the trails However the method leaves bandwidths of links upstream from the tokenholding node idle because the method only splits the original trail into two trails and leaves the upstream trail unsplit In this paper we propose a novel tokenpassing MAC method for further improving trail throughputs Our proposed method recursively splits the upstream trail and consequently the original trail can be split into more than two trails In the proposed method an appropriate setting of upstream/downstream tokenholding times of all nodes is a key factor to successfully accommodate an input traffic Therefore we tackle a problem called a tokenholding time decision problem where we optimize tokenholding times of all nodes so that input traffic is successfully accommodated We formulate the problem as a linear programming model Numerical examples on maximum effective throughput show that the proposed method is more superior as the ratio of shorthop traffic is higher in input traffic patterns
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