Optimal reserved resources to ensure the repetitions in ultra-reliable low-latency communication uplink grant-free transmission

Le, Trung-Kien; Salim, Umer; Kaltenberger, Florian
EUCNC 2019, European Conference on Networks and Communications, 18-21 June 2019, Valencia, Spain

To meet the strict requirements of Ultra-Reliable Low-Latency Communication in the uplink, grant-free uplink transmission has been specified, allowing the UE to transmit
data in a random-access fashion without first transmitting a scheduling request and then waiting for a uplink grant from the gNB. To further increase the reliability, these grant-free uplink transmissions can be repeated without waiting for HARQ feedback from the gNB. However, these repetitions have to happen within a certain interval to avoid a confusion in HARQ IDs of different HARQ processes. When a UE starts transmitting
late in the interval, it, therefore, can not exploit all the possible repetitions and thus reliability and latency decrease. In this paper, a scheme based on reserved resources is proposed to ensure the number of repetitions in a specific period. The size of each reserved resource is optimized depending on its position so as to reduce resource consumption. The scheme evaluated by theoretical analysis and numerical results shows its benefits to system performance.

Systèmes de Communication
Eurecom Ref:
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