Ho to Get all UnitGroup Names for an Unit?

prabhu.janakiraman, if You need to get all groups that one unit belongs to You can use such request:
https://hst-api.wialon.com/wialon/ajax.html?svc=core/search_items&params={"spec":{"itemsType":"avl_unit_group","propName":"sys_units","propValueMask":"290","sortType":"sys_name","propType":"list"},"force":1,"flags":1,"from":0,"to":0}&sid=<sid>
replace 290 with Your unit id.
But if You need to do this for all Your units - it is better to get all units, all groups and for each unit check if it belongs to each group without new requests.