Planning Cost-Efficient FiWi Access Network With Joint Deployment of FWA and FTTH

This paper investigates the deployment of a cost-efficient fiber-wireless (FiWi) access network with joint utilization of fixed wireless access (FWA) and fiber-to-the-home (FTTH) technologies. In this work, we consider that residential users over a geographical area are to be provided with network services, constrained by the available network resources. We explore the implementation of hybrid FiWi access network that integrates a fiber-based passive optical network (PON) and fifth-generation (5G) wireless access network to provide efficient network services. This paper proposes a methodology for topology optimization of FiWi access networks, considering the usage of three-dimensional (3D) beamforming and 3D resource grid for downlink transmission from the gNB to the users in 5G scenario. We derive the beam codebook and generate multiple beams to simultaneously serve the spatially separated users. We derive the closed-form expression for millimeter-wave channel model incorporating large-scale and small-scale parameters to compute the effective SINR of users. Further, we propose an optimization framework for optimal resource allocation (i.e., beam and resource block) by utilizing the 3D resource grid for downlink transmission. We perform extensive simulations to demonstrate the effectiveness of the proposed methodology for various 3GPP 5G outdoor propagation scenarios, viz., RMa, UMa, and UMi-street canyon.

I. Introduction

With the introduction of the fifth-generation (5G) technology, the ease, flexibility, and cost efficiency in deployment makes the fixed wireless access (FWA) a promising solution to deliver high-speed network services at remote locations [1], [2]. FWA is used to provide network services to users in situations where the optical fiber-based infrastructure (i.e., fiber-to-the-home (FTTH)) is either unavailable or prohibitively expensive to deploy. Therefore, FWA has become a popular choice for telecom operators such as Verizon, Samsung, Huawei, and AT&T [1], [2]. 5G FWA provides wireless connectivity to the users with the 5G next generation Node B (gNB), using the customer premises equipment (CPE) placed at the users’ locations [1]. Due to the use of 5G and newer technologies like beamforming, massive multiple input multiple output (MIMO), and operation in the mid-band and high-band frequencies, 5G FWA can support high downlink and uplink speeds [1]. Even though a fiber-based FTTH network can provide high-speed connectivity, and more reliable and secured network services (compared to FWA), FTTH deployment is more complex and time-consuming. Additionally, FTTH is more expensive to deploy compared to FWA, especially in areas with low population density or challenging terrain. Typically, FTTH networks are provided to users in case the FWA network is not available or cannot support the required data rate. Therefore, a joint deployment of FWA and FTTH-based access networks using the same network infrastructure is required to efficiently support the user data rate requirements. The joint deployment can be achieved through the implementation of a hybrid fiber-wireless (FiWi) access network, that integrates a fiber-based passive optical network (PON) for backhaul and a wireless access network, such as a wireless mesh network, 5G, or a combination of these technologies in the frontend [3], [4], [5]. Figure 1 shows an example 5G FiWi network setup with multistage time-division multiplexing PON (TDM-PON) with two power splitter (PS) stages and 5G gNBs. It consists of an optical line terminal (OLT) located at the central office, a primary PS (PPS) connected to OLT, and several secondary PSs (SPSs) connected to the PPS. An optical network unit (ONU) is placed at a fiber user (i.e., FTTH user) premises. Alternatively, an ONU may also serve a gNB through a hybrid module (ONU-gNB) [3], [4], [5], and CPE is placed at the wireless user (i.e., FWA user) premises [2]. Fig. 1.

Multistage TDM-PON and 5G-based FiWi network architecture.