## 6 Results and Discussion
Under the considered scenario and based on the results for ARPA2 topology, with a successful transmission of 85% of fronthaul traffic through the low-cost Ethernet infrastructure, a significant amount of CAPEX and OPEX, which  
Figure 5: Performance results for average queuing delays for the (**a**) COST239; and (**b**) ARPA2. would be required to deploy the complete optical fronthaul networks, can be saved. Hence, in this case, only 15% of the traffic required transmission through high-capacity and expensive optical links. For networks such as COST239, almost all of the traffic can be transported through the Ethernet systems, which would be highly cost-effective. The results in Figure 7 show the distances that different schemes can support under different traffic load conditions based on the latency constraints. The distances are computed based on Equations (1)-(5). The proposed LAPC and LAPF-FP schemes outperform the LLR and considerably improve the distances supported by the fronthaul links. It can be observed that with the LAPF-FP scheme, the distances of the fronthaul segment can be increased up to 30 km for 50 Gbps of traffic, which reduced with the increase of traffic load, as shown in Figure 7a. In ARPA2 topology, as the number of intermediate bridges and distances between the RRHs and BBU pool has been increased as compared to COST239. As a result, the processing, transmission, queuing, and encapsulations delays at each bridging node would also be increased, which resulted in high E2E latencies based on Equation (4), and low fronthaul distances based on Equation (5). As shown in Figure 7b, the proposed LAPF-FP scheme can support fronthaul link distances from 3 km to 18 km for 50 Gbps to 100 Gbps of traffic, respectively. In contrast, the existing scheme can only support a maximum link distance of 4.5 km in Ethernet-based fronthaul bridged networks. The simulation results showed that in about 50% of cases, the proposed LAPF-FP scheme minimized the queuing delays and worst-case E2E latencies by more than 110 us and 90 us, respectively, compared to the LLR. In about 70% of cases, our scheme improved the link distances up to 35% compared to the LLR. The results show that alone, delay-sensitive path computation schemes could not be enough to maximize the traffic transmissions in the EFBNs, and along with the path computation schemes, novel traffic forwarding concepts such as the one proposed in this study that enabled the frame preemption on high-load paths were required to fully exploit the advantages of leveraging Ethernet-based fronthaul networks. The simulation results showed a tradeoff between the maximum link distances and acceptable E2E latencies. By improving the E2E latencies in fronthaul networks, the length of Ethernet links can be increased. It can be concluded that with frame preemption in the proposed low-latency packet forwarding which is named the LAPF-FP scheme, the E2E latencies of maximum eCPRI streams can be retained closer to the threshold, and long-distance Ethernet links can be deployed between the RRHs and the BBU pool by fully satisfying the latency constraints of the fronthaul networks. However,  
Figure 6: Performance results for worst-case end-to-end (E2E) latency for (**a**) COST239; and (**b**) ARPA2. this type of performance is not guaranteed with the existing schemes, which makes them less suitable to addressing the latency constraints of Ethernet-based fronthaul bridged networks.