Optical module on the bbu side

The optical module on the BBU side converts electrical signals into optical signals for high-speed transmission to the RRU, supporting CPRI/eCPRI interfaces with specific rates, wavelengths, and duplex modes.Function and RoleThe BBU optical module serves as the transmitter and receiver interface between the Baseband Unit (BBU) and the Remote Radio Unit (RRU). It converts electrical baseband signals from the BBU into optical signals for transmission over fiber and converts incoming optical signals from the RRU back into electrical signals for processing . This enables high-speed, long-distance communication while maintaining signal integrity. The BBU is typically located indoors in a climate-controlled environment, while the RRU is mounted outdoors, making the optical module critical for reliable data transport .Types and SpecificationsOptical modules on the BBU side vary depending on network generation and interface requirements:4G Networks: Typically use 1.25G to 10G SFP/SFP+ modules with 850nm wavelength, supporting multimode fiber transmission distances of 300–550 meters .5G Networks: Use 25G SFP28 modules for eCPRI/CPRI interfaces, with multimode fiber distances up to 100 meters (OM4) or longer for single-mode modules .Duplex Modes: Modules can be duplex (two-fiber bidirectional) or BIDI (single-fiber bidirectional). The BBU and RRU must use compatible modules with matched transmit/receive wavelengths (e.g., 1270TX/1330RX on BBU and 1330TX/1270RX on RRU), .Industrial Requirements: While the BBU operates in a controlled indoor environment, modules may still need to meet IEC safety standards and support stable operation under varying power conditions .Installation and MappingOptical modules must be installed in pairs on both ends of the fiber. The rate of the optical module must match the CPRI/eCPRI port rate to avoid performance issues such as alarms, bit errors, or link interruptions . Only certified modules from the equipment vendor (e.g., Huawei) should be used to ensure compatibility and compliance with laser safety standards .Fault ConsiderationsCommon issues on the BBU side include Transmit/Receive faults, which can trigger alarms and affect the RF unit. These faults may result from power instability, incorrect module mapping, or mismatched wavelengths . Proper monitoring and maintenance of the BBU optical module are essential for network reliability.SummaryThe BBU optical module is a key component in mobile base stations, enabling high-speed, reliable communication with RRUs. Selection depends on network generation, interface type, transmission distance, and duplex mode. Correct installation, certified modules, and monitoring are critical to prevent faults and maintain network performance .