  Interference coupling in heterogeneous networks introduces the inherent
non-convexity to the network resource optimization problem, hindering the
development of effective solutions. A new framework based on multi-pattern
formulation has been proposed in this paper to study the energy efficient
strategy for joint cell activation, user association and multicell multiuser
channel allocation. One key feature of this interference pattern formulation is
that the patterns remain fixed and independent of the optimization process.
This creates a favorable opportunity for a linear programming formulation while
still taking interference coupling into account. A tailored algorithm is
developed to solve the formulated network energy saving problem in the dual
domain by exploiting the problem structure, which gives a significant
complexity saving compared to using standard solvers. Numerical results show a
huge improvement in energy saving achieved by the proposed scheme.
