A system and method includes implementing, by a base station (BS), a reliable ultra-low latency transmission mechanism in a grant-free uplink transmission scheme having defined therein contention transmission unit (CTU) access regions and a plurality of CTUs. Implementing the reliable ultra-low latency transmission mechanism includes defining a reliable ultra-low latency CTU (RULL-CTU) access region from a portion of the CTU access regions of the grant-free transmission scheme, defining an RULL-CTU mapping scheme by mapping at least a portion of plurality of CTUs to the RULL-CTU access region to define a plurality of RULL-CTUs, defining a reliable ultra-low latency user equipment (RULL-UE) mapping scheme by defining rules for mapping a plurality of RULL-UEs to the plurality of RULL-CTUs in an initial pattern for initial transmissions in a first transmission time interval (TTI), and a regrouped pattern for redundant transmissions in a second TTI subsequent to the first TTI.