Downlink - >At PGW, it receives plain IP packet which the complete IP header.
Based on the type of IP packet, PGW does packet filtering and place the filtered packet to the associated bearer.
Once the packet reaches at eNodeB, it removes the GTP header and does the IP header compression. The compressed IP packet sent to UE using the data radio bearers established UE and eNodeB.
Uplink -> In uplink direction, Filters present at UE side takes the responsibility to put originated IP packet into appropirate bearer and does the header compression before sending out the packet to UE. Once the packet reaches at eNodeB, it decompresses the packet and send the packet to SGW by using the associated tunnel id.
Are u looking something else ? you are fine with this description.