## 1 Introduction  
A main concept of Time Division Multiplexing-based Passive Optical Networks (TDM-PON) is a utilization of one shared Optical Line Terminal (OLT) transceiver for communicating with \(N\) distant Optical Network Units (ONU) using \(I\):\(N\) passive optical Power Splitter (PS) elements in the Remote Node (RN) location. All ONU units must by scheduled by means of dedicated time slots controlled by the OLT module. By this way, a number of requested optical components is minimized; however, a performance penalization is occurring at the optical power budget. A disadvantage of this network type is also the Time Division Multiple Access (TDMA) technique that requires a dynamic bandwidth allocation and some services substantial for the latency and the delay do not support it. Above-mentioned problems are not incorporated into future Wavelength Division Multiplexing-based Passive Optical Networks (WDM-PON) principles. In the WDM-PON network, the Arrayed Waveguide Gratings (AWG) element is used instead of the power splitter, and its loss is much lower. Moreover, a receiver bandwidth can be adjusted to a specific ONU data rate. An advantage of this network type is a direct connectivity between end points and therefore there is no problem with a quality of service because each user is not constrained by other users sharing the same optical infrastructure [1]. Frequently used acronyms and terms are presented in Table 11.  
The evolution of passive optical networks is oriented on larger geographical areas, higher numbers of subscribers, and higher bandwidth per subscriber. In [2], a comparison study of active and passive optical access networks utilizing the Point-to-MultiPoint (P2 MP) topology is presented without any protection scheme. A possible migration scenario to the next generation of hybrid passive optical access networks is presented in [3] also with a proposal for a self-restored architecture including the classical point-to-multipoint physical topology. In [4], a comparison of power budget analyses for single- and dual feeder fiber architectures of passive optical networks is presented. By means of power budget and transmission performances, a Hybrid Passive Optical Network (HPON) mechanism is analyzed in [5]. In [6], an effect of only fiber duplications on a protection feasibility of passive optical networks is analyzed. In [7], a wavelength reusable WDM-PON self-protected scheme is proposed with protective interconnection fibers used for achieving a whole distribution protection where each ONU is connecting with a ring. Protection mechanisms that can be applied for the whole long-reach passive optical networks are proposed in [8]. In [9], traffic protection schemes considered for these HPON networks are evaluated using the HPON Network Configurator [10; 11; 12]. Based on the used network topology, results of this evaluation are presented together with a recommendation that the hybrid and/or WDM-PON network deployment can be done with optimized protection mechanisms for a significant decrease in capital investments. It is profitable to keep at one's disposal an adequate number of reserve optical fibers and/or to provide protection mechanisms at the WDM-PON network deployment. WDM-based networks are considered with a protection and restoration for upgrading current optical access networks in [13]. For WDM-PON networks, a broadcast transmission method is proposed and experimentally implemented without a protection in [14]. In [15], a design and optimization of the hybrid WDM/TDM-PON network based on the ring-tree SARDNA architecture is proposed. An optical access network utilizing the Coarse Wavelength Division Multiplexing (CWDM) technique is proposed with the dual-rate dual-link architecture and with the P2 MP topology in [16]. A WDM-PON architecture with the P2 MP topology and with alternating optical fiber and optical wireless paths is expressed with a fiber fault protection in [17].