
16 ◾ IP Communications and Services for NGN
equipped with an IEEE 802.11 wireless LAN card. is card allows connection to
the Internet and to handle the network partitioning problem. en, the higher tier
is formed for a subset of mobile hosts and gateways, which can access the cellular
network. e higher tier is heterogeneous because it can support various network
interfaces in the gateway hosts, such as IEEE 802.11 cards, PHS handsets, or GPRS
handsets. Each interface supports different bandwidths and latency. Additionally,
by adopting the cellular internetworking interfaces on the higher tier, the mobil-
ity of the network will not be reduce ...