## 1 Introduction
This leads to potentially lower consumption of spectrum and transponders resources and thus allows to allocate more traffic in the network and increase the network capacity. According to our previous results presented in References [8; 11], full flexibility in the B2B regeneration, which means the possibility of regeneration with modulation conversion in each node traversed by a lightpath, can significantly increase the amount of served traffic in the network and thus provide higher network throughput without the need to upgrade the network by adding new fibers. Nevertheless, using the B2B regeneration complicates the network operation and optimization, since the basic optimization problem in SS-FONs (i.e., routing, spatial mode, and spectrum allocation (RSSA)) must be extended to account for allocation of transponders to lightpaths as well as for the fact that various nodes can be selected for regeneration. Another important aspect that may also have a large impact on the network throughput in the context of translucent networks with B2B regeneration is transponder placement (i.e., predeployment) which is a new--when compared to classic regenerators placement--optimization problem that appears here. As mentioned above, the key aspect of the B2B regeneration is the fact that transponders are used for two goals: transmitting/receiving (add/drop) of the signal at the source/destination nodes and regeneration of the signal at some intermediate nodes. In consequence, the placement of transponders must address these two potential usage scenarios of transponders, as the lack of free transponders can be the reason of request blocking when there are not enough devices to transmit, receive or regenerate optical signals. The previous works focused on regenerator placement have accounted only for the optical signal regeneration scenario, while the transponders used to transmit/receive the signal have been assumed to be unlimited in the network, and thus the transponder placement has not been addressed. Moreover, legacy regenerators receive a signal at a given data rate and, after regeneration, retransmit it with the same modulation format. To the best of our knowledge, the only paper that concerns the transponder placement problem in SS-FONs with B2B regeneration is our work [12] that presents some initial research in this topic. In this paper, as the main novelty and contribution, we present a new algorithm for transponder predeployment in SS-FONs with B2B regeneration. The reported results obtained by means of extensive simulation experiments, run on two representative network topologies with realistic assumptions, clearly show that our method outperforms other reference methods. Moreover, according to the recent trends in optical networking, in this paper we consider a data analytics approach assuming that the proposed algorithm is traffic and routing aware. We assume that based on historical data on network traffic or traffic prediction methods, we know the key characteristics of the traffic, which can be next used as an input to dynamic routing simulations. By these means, we can observe the network performance and collect various data that then are applied to improve network performance. To verify this approach, we ran experiments for five various traffic profiles, while the overwhelming majority of previous papers focusing on optimization of dynamic optical networks have assumed only one traffic profile based on uniform distribution of communicating nodes. In consequence, we provide a study showing how the network traffic characteristics influence performance of the algorithms and the general performance of the SS-FON. The rest of the paper is organized in the following way. In Section 2, we discuss related works. In Section 3, we describe the considered network and lightpath regeneration scenarios. In Section 4, we develop a transponder predeployment algorithm. In Section 5, we evaluate the algorithm performance with reference to other methods and analyze various network scenarios.