# Evolutionary Strategy for Practical Design of Passive Optical Networks
## 1 Introduction  
The emergence of new services using the Internet (applications such as video-on-demand, 3D high-definition television (TV), 4K, or 8K ultra-high definition (UHD), machine-to-machine (M2M), cloud computing, virtual/augmented reality (VR/AR) and fifth-generation mobile network (5G), for example) will require optical networks to transport traffic with different values of quality-of-service (QoS) and bandwidth requirements [1; 2; 3]. As reported by Cisco Systems [4], the number of global Internet users will be 5.3 billion (66% of the global population) by 2023. Fixed broadband speeds will be more than double by 2023. By 2023, global fixed broadband speeds will reach 110.4 Mbps, up from 45.9 Mbps in 2018. According to Federal Communications Commission's (FCC) broadband guide [5], a common house with regularly simultaneous uses of two or three devices, using applications thatrequire basic or moderate traffic (e.g., email, browsing, video, voice-over-internet protocol (VoIP) and at least one streaming HD video or an online gaming application), requires a service that offers a bandwidth of 12 to 25 Mbps. As a result, the consumer's demands may not be satisfactorily met if a high-quality access network service is not available in the subscriber's region. Broadband services have traditionally been provided over digital line subscriber (DSL) or cable modem networks [6]. However, it becomes even harder to support the fast-growing demand of users due to the fundamental bandwidth limitations of copper-based networks [7]. As a result, technologies based on optical fiber emerge as an alternative to meet these demands and the high quality-of-service required in access networks [8]. According to the Brazilian National Telecommunications Agency (ANATEL) report [9], in August 2019, approximately 65.2% of the Brazilian's access networks were still based on copper cables. However, it is worth mentioning the recent growth in the use of optical fiber (reaching the percentage of 26.3% on the same date). Another relevant piece of data is that only 46.7% of Brazilian households have fixed broadband access, which means that the optical fiber access network services will grow in the next few years. Several fiber access network architectures have been developed (e.g., point-to-point, active optical network and passive optical network) [10]. However, passive optical networks (PONs) stand out. A passive optical network means that it does not need electrical power in the outside plant. PONs' advantages include [11]: easy installation and updating; low cost of operation and maintenance; high reliability, electromagnetic immunity; and compact size cables. Nowadays, PONs have been launched into the practical market with Gigabit-capable PON (GPON), and following on from this, with its next generations XGS-PON and HS-PON (which are already standardized by ITU-T). Their ITU-T recommendations containing all technicals details are available in [12; 13; 14]. It should be noted that network designers and planners are therefore faced with several key challenges at all stages of the design process and this is not always an easy task, as many possibilities exist [15]. Thus, the PONs planning task can require several days to be completed, wasting resources that could be allocated to other assignment and demands. In this paper we propose an algorithm for PON planning based on the use of genetic algorithm (GA) technique. By using basic information such as streets, avenues, central office (CO) position, subscriber location and four possible topologies, the proposed algorithm finds a solution to the PON planning problem, considering four possible topologies in two simulation scenarios (non-dense and dense) and two different regions of interest. In the non-dense scenario, subscribers are distributed in a dispersed manner in the region of interest. The dense scenario has a considerably higher number of subscribers distributed very close to each other.