Future WLAN network is a heterogeneous mixture
network with a set of wireless access and mixed services.
With the support of converged network, users can switch
between different systems seamlessly, thus enjoying high
speed multimedia services. So providing seamless service to
meet customers' demand is the mark of successful wireless
communication systems in heterogeneous environments. In
addition, there are many communication blind zones for
WLAN in cities, due to radio waves attenuation and shadow
shade. Introducing ad hoc relay nodes in WLAN can
enhance data transmission capacity and improve network
coverage.