  Heterogeneous Networks (HetNets) are known to enhance the bandwidth
efficiency and throughput of wireless networks by more effectively utilizing
the network resources. However, the higher density of users and access points
in HetNets introduces significant inter-user interference that needs to be
mitigated through complex and sophisticated interference cancellation schemes.
Moreover, due to significant channel attenuation and presence of hardware
impairments, e.g., phase noise and amplifier nonlinearities, the vast bandwidth
in the millimeter-wave band has not been fully utilized to date. In order to
enable the development of multi-Gigabit per second wireless networks, we
introduce a novel millimeter-wave HetNet paradigm, termed hybrid HetNet, which
exploits the vast bandwidth and propagation characteristics in the 60 GHz and
70-80 GHz bands to reduce the impact of interference in HetNets. Simulation
results are presented to illustrate the performance advantage of hybrid HetNets
with respect to traditional networks. Next, two specific transceiver structures
that enable hand-offs from the 60 GHz band, i.e., the V-band to the 70-80 GHz
band, i.e., the E-band, and vice versa are proposed. Finally, the practical and
regulatory challenges for establishing a hybrid HetNet are outlined.
