25G/100G Module Technology Solutions in 5G Networks

1. Characteristics of 5G Networks

1.1 Large Bandwidth

1.3 Traffic Meshing

1.4 Network Slicing

1.5 Gradual Evolution from NSA to SA

2.25G/100G Optical Module Development Trends

3. Summary

Mobile communications network applications are currently transitioning from 4G to 5G. 5G (fifth-generation mobile communications technology) will rapidly develop and become a hot topic in the information and communications sector. The advanced construction and upgrade of bearer networks will drive a continued increase in demand for telecom network optical equipment. Simultaneously, demand for data center networks is exploding in the cloud computing era, and domestic internet companies, led by BAT, are entering a period of expanding IDC demand. This is leading to a rapid increase in demand for high-speed optical modules, such as 25G and 100G.

1. Characteristics of 5G Networks

5G mobile networks offer three major service categories: enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (uRLLC), and massive machine-type communications (mMTC). These services vary significantly in performance: eMBB targets traditional mobile communications and offers high bandwidth; uRLLC targets real-time control applications such as industrial automation and offers low latency and high reliability; and mMTC targets IoT applications, with multiple connections and low traffic.

The 5G radio access network (RAN) is restructured into active antenna units (AAUs), distributed units (DUs), and centralized units (CUs). The core network is shifting from centralized deployment in the 3G/4G era to a cloud-based, distributed deployment. Different service core networks are deployed in different locations to meet low-latency service requirements and improve user experience.

1.1 Large Bandwidth

Base station bandwidth depends on parameters such as radio spectrum bandwidth, spectrum efficiency, and the number of antennas. A 64-TR 100-Mbps base station can achieve a peak bandwidth of 6 Gbit/s and an average bandwidth of 3 Gbit/s. According to the International Telecommunication Union (ITU), the maximum peak bandwidth of a 5G base station can reach 20 Gbit/s. In practice, base station speeds cannot reach the maximum peak rate. Furthermore, due to cost and power considerations, various 5G base station types will coexist, with base station bandwidths ranging from 1 to 20 Gbit/s.

1.2 Low Latency

5G latency varies significantly across different services. The 3rd Generation Partnership Project (3GPP) TR 38.913 defines end-to-end (E2E) latency for eMBB as 10 ms and for uRLLC as 1 ms. The air interface latency for eMBB is 4 ms, and for uRLLC is 0.5 ms. However, 3GPP TS 22.261 V16.0.0 provides different latency definitions for different uRLLC services.

1.3 Traffic Meshing

5G CUs and DUs are flexible and can be split or merged. Distributed CUs and DUs have many-to-one or one-to-many connections, necessitating dual homing and redundancy requirements. With the phased introduction of eMBB, uRLLC, and mMTC services, the central network is gradually transitioning from centralized to distributed deployment. There is a many-to-many relationship between CUs and the core network, and traffic interaction exists between the core networks. In the 5G era, the trend toward mesh-based service traffic is becoming more pronounced.

1.4 Network Slicing

Next Generation Mobile Networks (NGMN), IMT 2020, and the 3rd Generation Partnership Project (3GPP) have all proposed network slicing architectures for 5G networks based on Software-Defined Networking (SDN)/Network Function Virtualization (NFV). Network slicing provides a foundation for future network innovation and rapid service deployment. Furthermore, network slicing services offer features such as management isolation, resource isolation, computing isolation, forwarding isolation, and control isolation. Flexible resource isolation can be configured to meet the differentiated security, reliability, and key performance indicators (KPIs) requirements of different services, ensuring service security and quality.

1.5 Gradual Evolution from NSA to SA

5G network deployment models are categorized into Standalone (SA) and Non-Standalone (NSA). In SA, a new wireless and core 5G network is built, with the 4G and 5G networks operating independently. NSA is a gradually evolving network technology solution that leverages existing 4G resources, enhancing the 4G network and providing 5G services through partial capacity expansion. As 5G services mature, it will gradually evolve to 5G. 5G bearer networks utilize 10 GE and 25 GE interfaces on the user network interface (UNI) side to connect to base stations. 25 GE, 50 GE, and 100 GE interconnect technologies will be introduced on the network side, and metropolitan areas may evolve to 200 GE and 400 GE links in the future. Therefore, 5G network construction will require optical modules featuring integration, miniaturization, high speed, long reach, low cost, and low power consumption, such as 25G and 100G optical modules.

2.25G/100G Optical Module Development Trends

The speed of optical modules has always been a focus of the market. These modules can be categorized into 622Mb/s, 1.25Gb/s, 2.5Gb/s, 10Gb/s, 40Gb/s, and 100Gb/s. Currently, several factors are driving optical module speed upgrades. First, the "Broadband China" strategy mandates 100Mbps fiber-to-the-home (FTTH). This increases pressure on optical interfaces at the access layer, and subsequently at all levels, driving demand for high-speed optical modules. Second, with the deployment of 5G, operators will need wider bandwidth to support high-volume data applications such as telemedicine, VR, and 4K video. Consequently, higher speeds are essential at all levels of mobile networks, driving the development of 25G and 100G optical modules.

In addition to the enormous demand for optical modules in operator networks, the accelerated construction of cloud computing data centers is also driving demand for 25G and 100G optical modules. Consequently, the demand for 100G optical modules driven by the construction and renovation of global data center networks will surge, and the high-speed optical module market is expected to remain robust.

Summary

In the 4G network era, optical modules benefited significantly from carrier optical network upgrades, the surge in demand for cloud computing data centers, and the growing demand for all-optical data centers, particularly 10G optical modules. It is believed that in the future 5G network era, 25G and 100G optical modules will lead the continued growth of the optical communications industry.