## 2 Materials and Methods
In [30], possibilities for selection of wavelength channels based on executed performance analyses of the FWM influence are presented for practical utilization in the DWDM communication system. This research work is focused on developing of future WDM-PON networks with new relevant technologies and related traffic protection schemes and on their performance analysis. The major contributions are listed below:  
* Summarize possible and expected architectures of advanced WDM-PON networks;
* Create and make considered presumptive scenarios for protection schemes in advanced WDM-PON networks. By reason of missing such traffic protection and restoration schemes in most of research contributions and scientific papers with WDM-PON network designs, we must propose, design and integrate traffic protection approaches for all possibilities of WDM-PON network architecture including also new protection schemes and mechanisms not considered and presented till now;
* Realize corresponding reliability block diagrams suitable for network availability considerations for protection schemes in advanced WDM-PON networks;
* Execute the performance analysis of WDM-PON protection schemes from a viewpoint of their network availability. For this aim, it is necessary to create, apply, and adjust general relations and formulas for calculation of the total network availability in specific protection scenarios;
* Because the optical power budget is a key parameter for real implementation of any WDM-PON network design, power budget considerations must be evaluated before the performance analysis of WDM-PON protection schemes from a viewpoint of their network availability. * Enable accommodation and re-adjustment of protection schemes according to network operators' demands from a viewpoint of utilized optical components, their parameters and operating traffic parameters associated with network operators' passive optical network infrastructures. * Design, create and realize a software tool that will incorporate all necessary relationships between optical components, their relevant parameters and values corresponding to reality and will evaluate a network availability according to network operators' demands. In this contribution, an importance and possible deployment scenarios of WDM-PON networks together with a network survivability and protection schemes are introduced. In addition, the aim of performance analyzing WDM-PON protection schemes is mentioned. The next sections are organized as follows: in Section 2, a basic classification of WDM-PON network architectures based on the topology is presented. Presumptive scenarios for P2 MP and RING protection schemes involved in the performance analysis of WDM-PON networks with corresponding reliability diagrams are presented in Section 3. Subsequently, their network availabilities are considered by the use of appropriate formulas and parameters. Because the power budget in passive optical networks is considered as an important standpoint, WDM-PON protection schemes are considered from this viewpoint and compared based on power budget requirements in addition. For analyzing network availabilities of various possible traffic protection schemes, a modification and extension of the PON Network Availability Evaluator is prepared and created (Section 4). In Section 5, considered protection schemes utilized in WDM-PON networks are evaluated and compared based on their total network availabilities. Moreover, a comparison of TDM-PON and WDM-PON network availabilities is included.