inted, with permission Mountaser et al. 2017 [6]. Minimum Minimum Minimum Average Average Average Maximum Maximum Maximum PDCP-RLC MAC-PHY Intra-PHY PDCP-RLC MAC-PHY Intra-PHY PDCP-RLC MAC-PHY Intra-PHY Figure 11.5 Latency from the upper to the lower layer for different splits for 5G services. (a) eMBB; (b) mMTC; (c) URLLC. Source: © 2017, IEEE Reprinted, with permission Mountaser et al. 2017 [6]. This is because, for the intra-PHY split, all 14 symbols, and thus the 14 packets, need to be transmitted by the DU for each transmission time. 1 In Figure 11.5 the focus is on the latency introduced by each split (i.e. the time interval from when a packet is transmitted by the CU to when the packet is successfully received by the DU). From Figure 11.5, we can observe that the average latency of PDCP-RLC and MAC-PHY splits is almost constant for all 5G services, which equals ~ 65 us for PDCP-RLC and ~60 us for MAC-PHY. Hence, the PDCP-RLC and MAC-PHY splits work in a more con- sistent way compared to intra-PHY in terms of average latency. While the average latency of the intra-PHY split is high and equal to ~ 810 us this is due to congestion caused by many packets to be sent in each transmission time. From latency point of view, PDCP-RLC and MAC-PHY are both suitable split options for URLLC and eMBB as being able to guarantee low latency. 1 This behavior is due to current OAI implementation; improvements could be achieved by employing, for example, compression and multiplexing. 11.4 Simulation Results Analysis of Multipath Packet-Based Fronthaul for RAN Slicing For mMTC, intra-PHY split may be a candidate solution for the following reason. All the traffic received by the CU (i.e. both user- and control-plane traffic) will be translated on the FH with a fixed data rate as it depends only on the channel bandwidth. This is benefi- cial especially for new technologies expected to be used for mMTC such as Narrow-Band Internet of Things (NB-IoT) [17]. 11.4 Simulation Results Analysis of Multipath Packet-Based Fronthaul for RA