Interconnection Between UMTS and WLAN Through Mobility Gateway

The interconnection architecture is presented in Figure 2.20. An intermediate
server (mobile proxy) is placed on either the UMTS or the IEEE 802.11
WLAN sides and the mobility gateway (MG) will handle the routing and
mobility issues.
When an MS is attached to an access point, the communication path
between the MS and a correspondent host (CH) on the Internet will be 1a-3.
The CH-MS communication path will be 4-2a. When the MS is on the
UMTS network, this path will be 1b-3, and the reverse path is then 4-2b. It should be observed that the segments 3 and 4 in both paths do not change
regardless of where the MS is located. Only the links 1 and 2 will be continually
changing, depending on the movement of the MS. Clearly, the communication
between MS and the proxy server alone is subject to change while
maintaining the proxy-CH connection unchanged supports mobility. On
protocol stacks architecture of the WLAN network nothing changes. The protocol
architecture of the UMTS network is a modification of which the MG is
placed next the GGSN part of the protocol stacks of the UMTS. On the MS,
there will be some protocols adopting if the user want roaming between both
networks when he or she is still in one of the network. So this function does
require a dual-mode stack implementation on the MS. Figure 2.21 shows the
protocol stack architecture for both the MG entity and the MS.