The flow of IP packets through the Satphone User Terminal involve several components described here.
In the outbound flow of traffic from the Terminal Equipment, a packet arrives at a UT network interface (USB, Wireless LAN, or Ethernet). The network interface receives the packet and passes it up the IP stack. The IP header is analyzed to determine the destination network interface that the packet is to be forwarded to.
The packet will match the default route in the routing table that will correspond to the satellite air interface. The forwarding function in the Hughes UT will pass the packet to the NAT module registered to the satellite air network interface. The NAT will maintain a mapping of to for each TE/PDP Context association.
The NAT modifies the IP header to substitute in the public IP address.
The packet is passed onto the UMTS interface driver.
The HNS-9201 will determine which PDP context the packet shall use to conform to the traffic flow template and quality of service requirements configured by the user.
The packet will then be passed to the Radio Access Bearer (RAB) for the proper PDP context for transmission over the BGAN satellite system.
The HNS-9201 will now pass the packet through the Packet Data Convergence Protocol (PDCP), Bearer Connection (BCn) Layer and the Bearer Control Layer (BCt) layers of the BGAN air interface protocol stack.
Incoming IP packets follows the same path as the outbound flow in the reverse direction.