Semi-Active WDM System for 5G Fronthaul Transmission

Semi-Active WDM System for 5G Fronthaul Transmission

Facilitates Rapid Deployment of 5G by Operators

1.1.Product Overview

After deploying 5G networks, the density of base stations will be 2 to 4 times that of 4G networks, and fiber constraints will be the main issue faced in 5G fronthaul deployment. To meet the rapid deployment of base stations and effectively save fiber resources in 4G and 5G network deployments, operators have adopted a solution combining WDM multiplexer and colored light modules to achieve low-cost, rapid coverage. However, there are also shortcomings and pain points in practical applications:

Passive WDM + colored light module mode has the following issues:

• Passive WDM lacks management and protection；
• Lack of management means；
• Weak ability to detect faults in fiber links；
• No protection for intermediate transmission fiber cores, requiring external OLP for implementation；
• Maintenance of optical modules heavily relies on manual intervention；

Solutions using active WDM or OTN technologies can solve the difficulties of network management and primary/backup route selection in optical paths, but they also face challenges such as high costs and difficulties in remote power supply.

Based on previous technical accumulations and research on active and passive WDM, and continuous in-depth understanding combined with customer pain points regarding fronthaul equipment carrying demands, Guangzhou Rui Dong has introduced a semi-active WDM as a solution for base station fronthaul.

The semi-active WDM solution uses active equipment on the local end and passive equipment on the remote end, facilitating deployment and maintenance. Through local equipment, it supports network management, line protection, and fast OTDR fault location functions. The maintenance methods are convenient and flexible, meeting high reliability requirements. This solution significantly alleviates the pressure on fiber resources, while also balancing cost, management, and protection advantages, thereby assisting operators in low-cost, high-bandwidth, and rapid deployment of 5G fronthaul networks.

This solution is suitable for scenarios with tight fiber resources at extended base stations, simple dual-star or bus-type network configurations (covering scenarios such as highways, high-speed railways, tunnels, bridges, etc.). It features colored light modules located on AAU and DU equipment, using WDM technology for transmission to save fiber resources and support OADM up/down wave functions. It can also utilize dual-route fiber cables for fronthaul service protection, while supporting legacy 4G fronthaul fibers, achieving unified fronthaul for 4G/5G.

Fig.1 Diagram of a semi-active WDM scheme

The networking architecture of semi-active wavelength division multiplexing (WDM) can be divided into star and bus topologies according to specific scenarios.

Figure 2 Semi-active WWD-star networking

Figure 3 Semi-active WDM bus networking

Device view

2.1. Local End Equipment

2.1.1.FW6600A - 1U Chassis