sisting of time and/or frequency information of the interrupted resources. This indicator helps users identify the reason for packet errors and what part of the packet is unaffected from the interruption. Retransmission of selected code blocks when the ongoing service is interrupted by the URLLC transmission is another solution, where part of the code block that has been affected by URLLC transmission is retransmitted. By transmitting a combining indicator or flush-out indicator, the receiver can perform the soft symbol combining of the transmitted and retransmitted code blocks. One can further achieve better coding gain by lowering the code rate of the retransmitted code block. An efficient scheduling scheme in terms of resource allocation and latency is to multiplex data with different transmission time lengths (i.e., mini-slots and slots) and in case of resource limitations to let the high-priority service use resources from lower priority ser- vice. This type of multiplexing is also referred to as preemption. For example, in NR downlink, a mini-slot carrying high-priority or delay-sensitive data can preempt an already ongoing slot-based transmission on the first available OFDM symbols without waiting for the next free resource. This operation enables ultra-low latency for mini-slot- based transmission, especially in the scenario where a long slot-based transmission has already been scheduled. A similar concept is also considered for the uplink and in general for LTE. At the cost of degrading the longer transmission, no additional resources need to be reserved in advance for the URLLC service. The impacted longer transmission is then 454 Chapter 4 promptly repaired with a transmission containing a subset of the code block groups in a later transmission time, after providing the essential information to clean the corrupted soft values in the receive buffer from the preempted data. If the URLLC transmission occurs frequently, the efficiency of the above approach will be reduced due to the fre- quent retransmissi