  This paper presents a unified mathematical paradigm, based on stochastic
geometry, for downlink cellular networks with multiple-input-multiple-output
(MIMO) base stations (BSs). The developed paradigm accounts for signal
retransmission upon decoding errors, in which the temporal correlation among
the signal-to-interference plus-noise-ratio (SINR) of the original and
retransmitted signals is captured. In addition to modeling the effect of
retransmission on the network performance, the developed mathematical model
presents twofold analysis unification for MIMO cellular networks literature.
First, it integrates the tangible decoding error probability and the abstracted
(i.e., modulation scheme and receiver type agnostic) outage probability
analysis, which are largely disjoint in the literature. Second, it unifies the
analysis for different MIMO configurations. The unified MIMO analysis is
achieved by abstracting unnecessary information conveyed within the interfering
signals by Gaussian signaling approximation along with an equivalent SISO
representation for the per-data stream SINR in MIMO cellular networks. We show
that the proposed unification simplifies the analysis without sacrificing the
model accuracy. To this end, we discuss the diversity-multiplexing tradeoff
imposed by different MIMO schemes and shed light on the diversity loss due to
the temporal correlation among the SINRs of the original and retransmitted
signals. Finally, several design insights are highlighted.
