How to use a base station optical module

To connect a base station optical module, insert the module into the BBU or RRU port, link it with the appropriate optical fiber, and ensure compatibility with the network interface (CPRI/eCPRI) and transmission standard.

Understanding the Base Station Setup

A base station typically consists of a BBU (Baseband Unit) and an RRU (Remote Radio Unit). The BBU handles signal processing, while the RRU transmits and receives wireless signals. In distributed sites, the RRU is mounted on the tower, and the BBU is located in the equipment room. The optical module and fiber serve as the transmission medium between these units, carrying high-speed data and physical layer information using protocols like CPRI for 4G or eCPRI for 5G networks .

Selecting the Optical Module

• 4G Networks: Use 1.25G SFP or 10G SFP+ modules. For example, a 10G SFP+ module with 850nm VCSEL laser can transmit up to 300m over multimode fiber .
• 5G Networks: Use 25G SFP28 modules for eCPRI interfaces, supporting distances up to 100m on OM4 fiber or longer with specialized modules .
• Ensure the module matches the fiber type (OM3/OM4) and the network interface standard.

Connection Steps

1. Insert the Optical Module: Carefully insert the SFP/SFP+ or SFP28 module into the designated port on the BBU or RRU. Ensure it clicks into place securely.
2. Connect the Optical Fiber: Attach the corresponding optical fiber to the module. Maintain proper polarity (Tx to Rx) and avoid bending the fiber sharply.
3. Verify Compatibility: Confirm that the module supports the required data rate (10G for 4G, 25G for 5G) and the protocol (CPRI/eCPRI).
4. Power On and Test: Power up the BBU and RRU, then check the link status. Use network management tools to verify signal integrity and data transmission.
5. Redundancy (Optional): For high reliability, use a fiber redundant architecture where a backup fiber and module can automatically take over if the primary link fails .

Additional Considerations

• Operating Temperature: Industrial modules often support -40℃ to 85℃, suitable for outdoor RRUs .
• Power Consumption: Typically less than 1W for SFP/SFP+ modules .
• Distance Limitations: Ensure the fiber length does not exceed the module's maximum transmission distance. For example, 10G SFP+ modules typically support 300m on OM3 fiber .
• Monitoring: Optical modules can also support fiber backhaul to the operator's core network for performance monitoring and remote management . By following these steps and selecting the correct optical module, you can establish a reliable high-speed connection between the BBU and RRU in both 4G and 5G base stations.