  The data center network (DCN), wired or wireless, features large amounts of
Many-to-One (M2O) sessions. Each M2O session is currently operated based on
Point-to-Point (P2P) communications and Store-and-Forward (SAF) relays, and is
generally followed by certain further computation at the destination.
%typically a weighted summation of the received digits. Different from this
separate P2P/SAF-based-transmission and computation strategy, this paper
proposes STAC, a novel physical layer scheme that achieves Simultaneous
Transmission and Air Computation in wireless DCNs. In particular, STAC takes
advantage of the superposition nature of electromagnetic (EM) waves, and allows
multiple transmitters to transmit in the same time slot with appropriately
chosen parameters, such that the received superimposed signal can be directly
transformed to the needed summation at the receiver. Exploiting the static
channel environment and compact space in DCN, we propose an enhanced Software
Defined Network (SDN) architecture to enable STAC, where wired connections are
established to provide the wireless transceivers external reference signals.
Theoretical analysis and simulation show that with STAC used, both the
bandwidth and energy efficiencies can be improved severalfold.
