  Multiuser Multi-Packet Transmission (MPT) from an Access Point (AP) equipped
with multiple antennas to multiple single-antenna nodes can be achieved by
exploiting the spatial dimension of the channel. In this paper we present a
queueing model to analytically study such systems from the link-layer
perspective, in presence of random packet arrivals, heterogeneous channel
conditions and packet errors. The analysis relies on a blind estimation of the
number of different destinations among the packets waiting in the queue, which
allows for building a simple, but general model for MPT systems with per-node
First-In First-Out (FIFO) packet scheduling. Simulation results validate the
accuracy of the analytical model and provide further insights on the
cross-relations between the channel state, the number of antennas, and the
number of active users, as well as how they affect the system performance. The
simplicity and accuracy of the model makes it suitable for the evaluation of
Medium Access Control (MAC) protocols for Ad-Hoc or Wireless Local Area
Networks supporting multiuser MPT in non-saturation conditions, where the
queueing dynamics play an important role on the achieved performance, and
simple user selection algorithms are required.
