A use case of shared 5G backhaul segment planning in an urban area José-Luis Romero-Gázquez 1 , Francisco-Javier Moreno-Muro 1 , Miquel Garrich 1 , María-Victoria Bueno-Delgado 1,3 , Pouria Sayyad Khodashenas 2 , Pablo Pavón-Mariño 1,3 1 Dept. Information and Communication Technologies Universidad Politécnica de Cartagena, Cartagena, Spain 2 i2CAT Foundation, Barcelona, Spain 3 E-lighthouse Network Solutions, Cartagena, Spain e-mail: {josel.romero, javier.moreno, miquel.garrich, mvictoria.bueno, pablo.pavon} @upct.es pouria.khodashenas@i2cat.net ABSTRACT This work presents a case study for the network planning of a 5G backhaul in a dense urban area. The study is fed by estimated population density data and real geographical layout coming from a Spanish city (Cartagena, around 220,000 population). The layout includes current locations of 4G base stations, which are assumed to place also new 5G macrocells, and real positions of lamp posts. The study assumes (i) an agreement among mobile operators to share the 5G network infrastructure, and (ii) a hypothetical agreement with the city hall, where the 5G deployment can be done by using city lamp posts for installing microcells, covering the city with a broadband 5G network outdoor access. An algorithm has been implemented to solve the dimensioning problem, as an Integer Linear Programming (ILP) technique. The deployment cost is proportional to the number of microcells to be installed in the study scenario. Results in terms of total number of microcells to be installed and traffic per microcell for different ratios of traffic demanded vs traffic carried are also analysed. The results can help mobile network operators to drive their strategic investment decisions. Keywords: 5G, backhaul, network planning, Net2Plan, GIS. 1. INTRODUCTION Mobile Network Operators (MNOs) are in a race against time to upgrade and expand their infrastructure to face the new and future mobile broadband services. 5G is in the nucleus of this network evolution, that promises an Internet of Everything (IoE) world with high data rates and low latency. In dense urban areas, one of the key approaches to target such requirements is network densification, placing 5G access cells closer to the users [1]. The economic impact behind the deployment of the 5G infrastructure is not easy to dimension. Since 5G is not yet commercialized, there are some uncertainties around technical and economic aspects, and the rollout strategies that MNOs will carry out. Some contributions have addressed this aspect, providing quantitative deployment evaluations of the 5G architecture [2]-[5]. Furthermore, the 5G deployment in the access is significantly affected by the radio propagation limitations. In previous works like in [6][7], the 5G dimensioning in dense urban areas has been evaluated, reporting the spectral efficiency, reflections, scattering and propagation loses, etc., at the frequency bands considered for 5G. These results motivate an approach (i.e. neutral hosting) for 5G deployment, where domestic and commercial venue owners have WiFi hotspots, picocells or femtocells in their own facilities, while outdoor microcells installed by telecom operators (e.g. building facades or lamp posts) should mostly cover outside users, and users in the vehicles. In this line, the present work focuses on the massive deployment of microcells to cover a medium size city (≈220,000 population), Cartagena (Spain). We assume that an agreement is made among MNOs to share the microcell deployment (multi tenancy). In addition, we assume that microcells can be placed at lamp posts, taking benefit of a hypothetical agreement between the city hall and the MNOs alliance (neutral host model). A Net2Plan [8] algorithm has been implemented to solve the dimensioning problem, modelled as an Integer Linear Programing (ILP) problem using the Java Optimization Modeler (JOM) [9]. This study explores the cost vs. city coverage trade-off in a real city layout and reports relevant performances, like the number of microcells to install, and the traffic that each microcell will carry out. The results of this work can give light to 5G roll out decisions and may help MNOs in their strategic investment. The rest of the paper is organized as follows: Section 2 explains 5G backhaul physical architecture. Section 3 describes the 5G dimensioning problem addressed and Section 4 presents the ILP developed to solve it. Section 5 shows the results of the ILP under different scenarios. Finally, Section 6 concludes the paper. 2. 5G BACKHAUL PHYSICAL ARCHITECTURE Fig. 1 illustrates the assumed 5G network, with optical and wireless technologies. In the backhaul, microcells can be wireless connected to a macrocell or wired connected to the wavelength division multiplexing passive optical network (WDM-PON). WDM-PON delivers a wavelength-based point-to-point connectivity between macrocells and microcells, and the Central Office (CO). This point-to-point connection requires an optical network unit