Mobility effects to protocol stack

At the data link layer, mobility based on wireless
networks brings problems of bandwidth, reliability, and
security, for which compression, encryption, and error
correction techniques are needed. Other problems include
fixed or dynamic channel allocation algorithms, collision
detection and avoidance measures, QoS resource
management, etc.

At the network layer, mobility of mobile nodes means
that new routing algorithms are needed in order to change
the routing of packets destined for a moving node to its new
point of attachment in networks. How to track a node’s
movement and how to keep the moving node’s connectivity
are two basic issues at the network layer. This in turn forms
the two main operations of mobility management.

At the transport layer, a end-to-end connection may
mix wired and wireless links. This makes congestion control
a complex task due to the different characteristics of wired
and wireless networks, since packet loss is caused mainly by
high error rates and handoff in wireless networks instead of
because of congestion—the situation on wired links.
Retransmission mechanism based on increasing interval
may lead to an unnecessary drop in the date rate. Function
distribution between the transport and the data link layer is a
new problem caused by mobility.