Energy Efficient NDMA Multi-packet Detection with Multiple Power Levels

Multi-packet detection approaches handle packet collisions and errors by forcing packet retransmission and by processing the resulting signals. NDMA (Network Diversity Multiple Access) detection approach forces Q retransmissions by all stations when Q stations transmit in one collision slot. Previous work assumed that perfect power control is used, where the average reception power is equal for all stations. In this paper we handle the scenario where no power control is used, and multiple power levels are received. We propose a modification to the basic NDMA (Network Diversity Multiple Access) reception mechanism, where some of the stations may not retransmit its packets all the times. This paper evaluates the EPUP (energy per useful packet) and the goodput for a saturated uplink. Our analytical results are validated by simulation using joint PHY (physical layer) and MAC (Medium Access Control) behavior. We show that by suppressing some retransmissions we are able to improve the system's EPUP, practically without degrading the network goodput.