The 5G network architecture was introduced by the 3GPP, a consortium of various standards organizations that develop protocols for mobile communications. This architecture represents an extension and enhancement of its predecessor, the 4G LTE network. Due to the complex design requirements needed to support the wide range of 5G applications, many of which demand high data throughput and long-distance signal propagation, the 5G network architecture must encompass both FR1 (low- and mid-band) and FR2 (high-band, mmWave) spectrums. These frequencies include licensed, unlicensed/shared, and existing bands, as shown in Figure 1.

                                                                         Figure 1: 5G spectrum outlined by country. Source: Quadcomm .

Figure 2 highlights three core frequency bands in the 5G network, each with distinct coverage distances:

1. Low-Band and Lower Mid-Band (4G LTE): Represented by the outermost circle, this band operates between 698 MHz and 2690 MHz, offering coverage up to 150 km. These frequencies, also part of the 5G NR bands, provide similar performance to 4G LTE and support the existing LTE/5G infrastructure in current 5G devices.
2. Mid-Band: This band includes 5G NR bands n77/n78/n79 (3300–5000 MHz) and NR-U bands n46/n96 (5150–7125 MHz). Frequencies between 3300 and 5000 MHz serve as a capacity layer for urban and suburban areas, with outdoor coverage ranging from 500 to 2500 meters and peak data rates in the hundreds of Mbps, especially with Microcell deployment in urban environments.
3. High-Band (mmWave): Operating between 24 and 100 GHz, this band offers the highest frequencies in 5G. However, signal strength in this range is heavily impacted by atmospheric absorption and obstructions like buildings and vegetation, limiting it to short-range coverage. Figure 2 shows that high-band deployments need dense network topologies, with Inter-Site Distances (ISD) around 150 to 200 meters. The commercialization of high-band 5G is challenging, as it requires numerous small cells (like Femtocells and Picocells) with coverage radii of less than 500 meters. This extensive infrastructure investment presents a barrier to rapid high-band deployment.

Figure 2: The three frequency bands at the core of 5G network. Source: DIGI.

A complete 5G network system requires an evolved network infrastructure, progressing from 4G LTE. Figure 3 shows this evolution, starting with the Non-Standalone (NSA) 5G network, which relies on 4G LTE infrastructure. Through EN-DC dual connectivity (E-UTRAN New Radio-Dual Connectivity), 5G users benefit from increased capacity by connecting to both 4G LTE and 5G networks. This is particularly useful during the transitional phase, allowing NSA users to experience faster speeds than standard 4G LTE.

Figure 3:  Evolution from the 4G network to 5G SA infrastructure. Source: OPPO.

The standalone (SA) 5G network, on the other hand, represents the true 5G network, featuring a dedicated 5G core that enables multi-Gigabit per second speeds and ultra-low latency. Because the SA network operates independently of 4G, devices supporting both SA and 4G networks are considered dual-mode 5G devices.

To further explore 5G’s cellular architecture and essential technologies, researchers have proposed a new heterogeneous 5G cellular structure that separates indoor and outdoor applications. This architecture leverages a Distributed Antenna System (DAS) and massive MIMO technology. Readers interested in 5G advancements can find valuable insights into challenges in 5G wireless technology, such as cognitive radio networks, mobile Femtocells, edge computing, and network slicing.

Feel free to contact me via email for collaboration: hisyam@umpsa.edu.my

Figure 4: 5G Grant