Efficient Bandwidth Allocation for URLLC in Frequency-Selective Fading Channels

In this paper, a multi-user system adopting finite blocklength (FBL) channel codes for downlink (DL) transmissions under quality-of-service (QoS) constraints is considered. A framework for minimizing the total bandwidth to ensure ultrareliable and low-latency communications (URLLC) between a transmitter and multiple users is established. Frequency-selective fading channels are considered. It is assumed that channel state information (CSI) is perfectly known at the receiver. Effective capacity framework is employed to characterize the throughput under delay constraints with FBL channel codes. The relationship between the throughput and the bandwidth is studied. The optimization problem to minimize the total bandwidth under different QoS and minimum throughput limits is formulated. Furthermore, an efficient algorithm to obtain the optimal bandwidth allocation scheme is proposed. Overall, the impact of delay exponents, decoding error probability and minimum throughput on URLLC is characterized.