## 7 Conclusions  
We proposed the end-to-end (E2E) latency-aware path computation (LAPC) scheme to improve the link utilization in capacity constraint Ethernet-based fronthaul bridged networks (EFBNs). The path computations were performed by primarily focusing on the E2E latency constraints of the eCPRI traffic streams. The latency-aware path selection scheme assures the lowest E2E latencies in the fronthaul bridged networks by considering the frame level queuing delays of eCPRI bursts. The performance of the EFBNs was further improved by exploiting the concepts of frame preemption in the proposed low-latency packet forwarding scheme, which is named the LAPF-FP. The LAPF-FP scheme reduces the queuing delays of high-latency experiencing RRHs (remote radio heads) streams by slightly increasing the queuing delays of the low-latency experiencing RRHs streams without the degradation of the overall system performance. The simulation results confirmed that the LAPF-FP scheme considerably reduced the E2E latencies and intensified the low-cost Ethernet systems to transport the time-sensitive eCPRI traffic up to 100 Gbps at tolerable latencies. Moreover, the low E2E latencies due to the LAPF-FP scheme significantly improved the link distances between the RRHs and the baseband unit (BBU) pool. This led to an expectation that the leveraging Ethernet systems could be a promising solution to implement the fronthaul bridged networks in the future cloud radio access networks (C-RANs). In summary, the following are the key findings from this study:  
1. This study considered the queuing delays and end-to-end latencies for computing and selecting the optimal paths for individual eCPRI traffic streams in the EFBNs.
2. A novel packet forwarding mechanism for equal priority eCPRI streams has been proposed that maximizes the transmissions of multiple eCPRI streams at tolerable latencies as well as improves the link distances between the RRHs and the BBU pool.
3. The simulation results showed that in about 50% of cases, the proposed scheme minimized the queuing delays and worst-case E2E latencies by more than 110 us and 90 us compared to the LLR. In about 70% of cases, our scheme improved the link distances up to 35% as compared to the LLR. This level of performance is not guaranteed with the existing schemes.  
Figure 7: Fronthaul distances supported by the different schemes for the (**a**) COST239; and (**b**) ARPA2.  
With the proposed schemes, time-sensitive eCPRI streams can be transported through the leveraging Ethernet links, which significantly reduced the CAPEX and OPEX of deploying extortionate optical-based fronthaul bridged networks in envisioned 5G cloud-RANs.  
Conceptualization, M.W., and A.K.; methodology, M.W.; software, M.W.; validation, M.W., and A.K.; formal analysis, A.K.; investigation, M.W.; resources, A.K.; data curation, M.W.; writing--original draft preparation, M.W.; writing--review and editing, A.K.; visualization, A.K.; supervision, A.K.; project administration, A.K.; funding acquisition, A.K.  
This work was supported in part by the National Research Foundation (NRF) and Ministry of Science, ICT and Future Planning (MSIP) of South Korea under grant number 2018R1D1A1B07049877.  
The authors declare no conflict of interest.