Hi dear,
In the eLTE Trunking(3GPP) 5.1 version, the biggest change is that the eUDC660 can be deployed independently, and there are also some changes in capacity indicators.
For more details, refer to the link:
https://support.huawei.com/hedex/hdx.do?docid=EDOC1100071716&id=EN-US_TOPIC_0142485162&text=Change%252520History&lang=en