Photon Netw Commun DOI 10.1007/s11107-012-0384-9 Novel strategies for sparse regenerator placement in translucent optical networks Daniel A. R. Chaves · Renan V. B. Carvalho · Helder A. Pereira · Carmelo J. A. Bastos-Filho · Joaquim F. Martins-Filho Received: 27 January 2012 / Accepted: 19 April 2012 © Springer Science+Business Media, LLC 2012 Abstract In this paper, we propose two strategies for sparse regenerator placement (RP) in translucent optical networks, named most used regenerator placement (MU-RP), and most simultaneous used regenerator placement (MSU-RP). Our proposals are compared to well known RP algorithms pre- sented in literature for two different network topologies for different network loads, distribution of load along the net- works and number of translucent nodes. MSU-RP presented remarkable results and outperformed all previous approaches in all cases, while MU-RP obtained a slightly superior or similar performance when compared to previous approaches presented in the literature. Keywords Optical networks · Translucent optical networks · Sparse regeneration · Regenerator placement · Regenerator allocation D. A. R. Chaves · H. A. Pereira · C. J. A. Bastos-Filho Polytechnic School of Pernambuco, University of Pernambuco, Recife, PE, Brazil e-mail: daniel.rchaves@ufpe.br H. A. Pereira e-mail: helder.pereira@poli.br C. J. A. Bastos-Filho e-mail: carmelofilho@ieee.org R. V. B. Carvalho · J. F. Martins-Filho (B ) Department of Electronics and Systems, Federal University of Pernambuco, Recife, PE, Brazil e-mail: jfmf@ufpe.br 1 Introduction Optical networks emerged as a promising solution to pro- vide infrastructure to deal with the ever-growing bandwidth demand generated by the recent released telecommunications services [1]. In the first generation of optical networks, all the network nodes were opaque. This means that an optical to electri- cal and an electrical to optical conversion (O/E/O) has to be accomplished in all nodes of the lightpath, i.e. the optical sig- nal needs to be converted to the electrical domain at each node of the lightpath, then the signal has to be electronically processed and reconverted to the optical domain [2]. These networks require an excessive number of O/E/O interfaces, which increases the overall capital expenditure (CAPEX) and operational expenditure (OPEX) of the network. The CAPEX is related to the cost of these interfaces, while the OPEX is related to the energy consumption and the maintenance issues. On the other hand, these O/E/O interfaces permit to restore the quality of the optical signal by performing re-amplification, re-formating and re-timing (3R regeneration) [2]. An alternative to the opaque networks is to avoid the use of O/E/O interfaces by routing the signal in the opti- cal domain along the core nodes. This solution is referred in the literature as all-optical networks or transparent optical networks [2]. In these networks, the optical signal propa- gates from the source node to the destination node with no O/E/O conversion. In general, all-optical networks present lower CAPEX and OPEX, but are more susceptible to the impairments imposed by the physical layer. It occurs since no 3R regeneration is performed and the penalties generated by the impairments are accumulated for several fiber spans and devices. Translucent optical networks (TON) can be viewed as an interesting solution to deal with this trade-off, by balancing 123