  Motivated by the promising benefits of dynamic Time Division Duplex (TDD), in
this paper, we use a unified framework to investigate both the technical issues
of applying dynamic TDD in homogeneous small cell networks (HomSCNs), and the
feasibility of introducing dynamic TDD into heterogeneous networks (HetNets).
First, HomSCNs are analyzed, and a small cell BS scheduler that dynamically and
independently schedules DL and UL subframes is presented, such that load
balancing between the DL and the UL traffic can be achieved. Moreover, the
effectiveness of various inter-link interference mitigation (ILIM) schemes as
well as their combinations, is systematically investigated and compared.
Besides, the interesting possibility of partial interference cancellation (IC)
is also explored. Second,based on the proposed schemes, the joint operation of
dynamic TDD together with cell range expansion (CRE) and almost blank subframe
(ABS) in HetNets is studied. In this regard, scheduling polices in small cells
and an algorithm to derive the appropriate macrocell traffic off-load and ABS
duty cycle under dynamic TDD operation are proposed. Moreover, the full IC and
the partial IC schemes are investigated for dynamic TDD in HetNets. The user
equipment (UE) packet throughput performance of the proposed/discussed schemes
is benchmarked using system-level simulations.
