  In this paper, we investigate centralized scheduling strategies for
cooperative incremental redundancy retransmissions in the slow-fading
half-duplex multiple access multiple relay channel. Time Division Multiple
Access is assumed for the sources and the relays. Sources transmit successively
in time slots for the first phase. The second phase consists of a limited
number of time slots for retransmissions. In each time slot, the destination
schedules a node (being a relay or a source) to retransmit, conditional on the
knowledge of the correctly decoded source sets of each node (which is itself
for a source). A scheduled relay retransmission uses Joint Network and Channel
Coding on its correctly decoded source messages (cooperative retransmission).
Several node selection strategies are proposed based on the maximization of the
long-term aggregate throughput under a given constraint of fairness.
Monte-Carlo simulations show that these strategies outperform the state of the
art one based on the minimization of the probability of the common outage event
after each time-slot. Moreover, the long-term aggregate throughput reached with
these strategies is close to the upper-bound, calculated by the exhaustive
search approach. The same conclusion remains valid for both symmetric and
asymmetric source rate scenarios.
