Hello!
The ODU is the outdoor unit of the microwave system. The ODU is mainly used to convert the frequency or amplify the power of the signals.

For more information,please click the following link
https://support.huawei.com/hedex/hdx.do?docid=EDOC1100113369&id=EN-US_CONCEPT_0120626174&lang=en
Hope my answer can help you, thank you