5G Technology: The New Mobile Communication Revolution and Its Architecture
A comprehensive technical review of how 5G is transforming the internet world through millimeter waves, polar codes, and service-based architecture.
In today's modern digital era, 5G is a major technological revolutionary shift in the field of wireless communication. First specified in Release 15 of the 3rd Generation Partnership Project (3GPP), the 5G network is the successor to 4G LTE. Prepared under the International Telecommunication Union (ITU) IMT-2020 framework, this technology is not limited to smartphones alone, but is an important foundation for industrial automation, smart cities, and the Internet of Things (IoT).
Compared to 4G, the 5G network is designed to provide higher data rates, lower latency (the time delay for a signal to reach its destination), and massive network capacity. According to ITU regulations, under ideal conditions, the maximum downlink speed of 5G can reach up to 20 Gbit/s and the uplink speed up to 10 Gbit/s. However, in practical use, actual consumer speed depends on factors such as spectrum band, network load, and distance from the tower.
History and Evolution: From 2008 to Commercial Rollout
The journey of 5G began in the year 2008 when NASA and M2Mi Corporation started research on nanosatellite communication. Subsequently, in 2012, the 'NYU Wireless' center was established by New York University, which conducted deep research on millimeter-wave communication. That same year, the 5G Innovation Centre was established at the University of Surrey in the UK with £35 million in funding, in which giant companies like Huawei and Samsung became partners. The European Union also played an important role in setting global standards through the METIS project.
In the year 2013, ITU-R Working Party 5D initiated studies for IMT-2020. During this period, Samsung successfully tested a speed of over 1 Gbit/s at a distance of 2 kilometers using an 8 × 8 MIMO antenna system. At the same time, Huawei announced a massive investment of $600 million for the development of this technology.
On April 3, 2019, South Korea made history by launching the world's first full national 5G network. South Korea's rollout utilized equipment from Samsung, Ericsson, and Nokia, while LG Uplus deployed Huawei hardware. More than 86,000 towers operating on the 3.5 GHz band were established in South Korea, where average download speeds of 200 to 400 Mbit/s were recorded, and by the end of 2019, the number of subscribers grew from 260,000 to reach 4.7 million.
| Detail | FR1 (Sub-6 GHz) | FR2 (mmWave) |
|---|---|---|
| Frequency range | 410 MHz to 7,125 MHz | 24,250 MHz to 71,000 MHz |
| Maximum carrier bandwidth | Up to 100 MHz | Up to 400 MHz |
| Signal distance/coverage | Large area (in kilometers) | Short distance (in hundreds of meters) |
| Typical download speed | 5 to 900 Mbit/s | Multi-gigabit (over 1 Gbit/s) |
| Obstruction effect (wall/tree) | Low effect | Easily blocked |
Network Modes: The Difference Between NSA and SA Architecture
5G networks are primarily deployed in two types: Non-Standalone (NSA) and Standalone (SA). In the initial stages, most operators chose the NSA mode, in which the existing 4G core network (EPC) is used as the control plane and the new 5G radio access network is used for data transfer.
On the other hand, the Standalone (SA) mode operates entirely on an independent 5G core (5GC). It does not depend on the older 4G infrastructure, which increases network efficiency and reduces operational costs. T-Mobile US launched the world's first national SA network in 2020. The SA mode enables advanced features such as network slicing and ultra-reliable communication.
For the efficient use of spectrum, the Dynamic Spectrum Shrinking or Dynamic Spectrum Sharing (DSS) technique is used. DSS technology allows 4G LTE and 5G NR to operate simultaneously in real-time on the same radio frequency carrier, allocating the spectrum based on time according to the user's requirement.
Spectrum and Frequency Ranges: FR1 and FR2
According to 3GPP specifications, 5G New Radio (NR) is divided into two main frequency ranges: FR1 (Frequency Range 1) and FR2 (Frequency Range 2). FR1 is generally known as Sub-6 GHz, covering frequencies from 410 MHz to 7,125 MHz. In this, the channel bandwidth is up to 100 MHz and its download speed is generally 5 to 900 Mbit/s.
The FR2 range is called millimeter wave (mmWave), operating between 24,250 MHz and 71,000 MHz (24.25–71 GHz). In this band, a wide bandwidth of up to 400 MHz per carrier is obtained, which is capable of delivering multi-gigabit speeds. However, mmWave signals travel very short distances and are easily blocked by walls, glass, or tree leaves. Therefore, its use remains limited to stadiums or dense urban areas.
Auction 107 (C-band auction) organized by the FCC for spectrum allocation in the United States received bids of over $81 billion, with Verizon spending $45.5 billion (56 percent) and AT&T spending $23.4 billion. Furthermore, under the 'One Big Beautiful Bill Act' signed into law on July 4, 2025, for the upper C-band (3.98 to 4.2 GHz), provisions have been made to auction an additional 100 to 180 MHz of spectrum by July 4, 2027.
- 1. Radio signal connectionUser Equipment (smartphone) connects with the nearby gNodeB (5G base station) via wireless RF signal.
- 2. Beamforming and frequency allocationgNodeB concentrates the signal towards the user via massive MIMO and beamforming and determines the appropriate subcarrier spacing.
- 3. Service-based core requestgNodeB sends a request to the control plane network functions (such as AMF, SMF) of the 5G Core (5GC) via backhaul connection.
- 4. User plane data transferAfter authentication is complete, the user's data connects directly to the Internet or private network through the User Plane Function (UPF).
Foundational Technologies of 5G: Massive MIMO, Beamforming, and Polar Codes
Behind the high capacity of 5G lie several important engineering techniques. The first among them is Small Cells, which are low-power radio nodes. To maintain mmWave signal coverage in dense areas, small cells are installed at intervals of a few hundred meters.
The second major technology is Massive MIMO. Unlike conventional systems, Massive MIMO uses massive antenna arrays on towers. This technique can send data to multiple users simultaneously and drastically increases spectral efficiency.
The process of concentrating radio energy emitted from the antenna toward a specific user rather than spreading it in all directions is called Beamforming. Analog beamforming increases signal strength, while digital beamforming improves signal quality by transmitting multi-layer data streams. Furthermore, by using Non-Orthogonal Multiple Access (NOMA) in 5G, more users can be connected on the same frequency through different power levels.
To correct data transmission errors, a new channel coding method has been adopted in 5G NR. In place of the turbo codes used in 4G, 5G uses Polar Codes for control channels and Low-Density Parity-Check (LDPC) codes for data channels. In Sub-carrier spacing (SCS), there are seven options ranging from 15 kHz to 240 kHz, where the cyclic prefix interval becomes as minute as dropping from 4.7 μs to 0.29 μs.
5G Core Architecture: Service-Based Design (SBA)
The 5G Core Network (5GC) is entirely based on a software-defined and service-oriented architecture. Instead of 4G's Evolved Packet Core, it uses a modular, software-based Service-Based Architecture (SBA). This system incorporates Software-Defined Networking (SDN) and Network Function Virtualization (NFV).
In SBA, each network function communicates with one another independently via RESTful APIs. Every function registers in the Network Repository Function (NRF), so the entire network can be easily scaled as needed. For central data processing, the Control Plane and User Plane have been completely separated (CUPS).
To securely connect non-3GPP networks (such as home Wi-Fi) to the 5G core, supporting components such as the Non-3GPP Interworking Function (N3IWF), Security Edge Protection Proxy (SEPP), and Trusted WLAN Interworking Function (TWIF) operate.
3GPP Releases and the Future: 5.5G and NR-Advanced
For the continuous development of 5G, phased releases are issued by 3GPP. Release 15 laid the foundation for 5G, while Release 16 (June 2020) and Release 17 (June 2022) added enhancements such as satellite networks and NR-Unlicensed (NR-U). Currently, work on Release 18 is underway by 3GPP, which is known as 'NR Advanced' or 5.5G.
In NR Advanced, the focus has been placed on Extended Reality (XR), the integration of Artificial Intelligence (AI/ML), and lower-layer triggered mobility instead of Layer-3. Huawei, Ericsson, Nokia, Qualcomm, Samsung, and ZTE are the major suppliers in the global 5G market. According to 2023 reports, Huawei accounted for approximately 70 percent of 5G base stations worldwide.
According to Ericsson's estimates, 5G networks will reach nearly 65 percent of the world's population by the mid-2020s. 4G and 5G networks will coexist for many years to come, but the standalone 5G core and the increasing use of millimeter waves will become the main pillars of the future digital revolution.
