  The densification and expansion of wireless network pose new challenges on
interference management and reducing energy consumption. This paper studies
energy-efficient resource management in heterogeneous networks by jointly
optimizing cell activation, user association and multicell multiuser channel
assignment, according to the long-term average traffic and channel conditions.
The proposed framework is built on characterizing the interference coupling by
pre-defined interference patterns, and performing resource allocation among
these patterns. In this way, the interference fluctuation caused by
(de)activating cells is explicitly taken into account when calculating the user
achievable rates. A tailored algorithm is developed to solve the formulated
problem in the dual domain by exploiting the problem structure, which gives a
significant complexity saving. Numerical results show a huge improvement in
energy saving achieved by the proposed scheme. The user association derived
from the proposed joint resource optimization is mapped to standard-compliant
cell selection biasing. This mapping reveals that the cell-specific biasing for
energy saving is quite different from that for load balancing investigated in
the literature.
