Replacing an RRU interrupts all the services carried by the RRU and causes alarms. You must disconnect optical fibers from an optical module before replacing. This chapter describes the procedures and precautions for replacing a common RRU, replacing a blade RRU, and replacing a non-blade RRU with a blade RRU by reusing mounting kits. An optical module implements. When replacing an optical module, do not look into the optical port without eye protection. If LTE is used rather than LTE FDD or LTE TDD in this document, the LTE mode can be the LTE FDD mode or LTE TDD mode. When powering off the RRU, you can perform normal power-off or emergency power-off operation based on field requirements.