# Highest Cost First-Based QoS Mapping Scheme for Fiber Wireless Architecture
## 5 Simulation Setup and Results
After STA, the \(\text{n}^{\text{th}}\) packet arrives at the wireless access point (WAP), and \(\text{APT}_{\text{N}}\) represents the processing time of the \(\text{n}^{\text{th}}\) packet at WAP. The WAP forwards the \(\text{n}^{\text{th}}\) packet via Ethernet link to the XGPON side and consumes \(\text{T}_{\text{XGPON}}\) as the sum of packet processing time from ONU to OLT using Equation (9). \[\text{EE}_{\text{Delay}}=\text{AT}_{\text{N}}\cdot(\text{GT}_{\text{N}}+\text {TT}_{\text{N}}+\text{APT}_{\text{N}}+\text{T}_{\text{XGPON}}) \tag{8}\]  
\[\text{T}_{\text{XGPON}}=\text{PT}_{\text{ONU}}+\text{PT}_{\text{OLT}} \tag{9}\]  
Figure 7 shows the \(\text{EE}_{\text{Delay}}\) analysis of four concurrent UDP streams, i.e., VO (T1), VI (T2), BK (T3), and BE (T4), in DCF and EDCA mode. Each stream is mapped with different TCONTs of XGPON as explained in Section 3. \(\text{EE}_{\text{Delay}}\) in both DCF and EDCA increases from low to high as the load increases, which is absolutely rational, however, compared to DCF, the EDCA delay is lower at higher traffic loads due to the traffic priority mechanism and HCF algorithm. Since DCF uses a single first-in first-out (FIFO) queue to handle all the traffic classes, its \(\text{EE}_{\text{Delay}}\) is higher than the EDCA method in FiWi access network topology for all the T1 to T4 TCONTs. Thus, from Figure 8a, it is evident that the US delay of voice traffic is almost linear in the EDCA model, and in the case of DCF, it is lower at lower load but as the load increases, the delay of voice traffic also increases. Similarly, the video traffic having the second highest priority in EDCA mode, being mapped to T2 with guaranteed bandwidth, also behaves quite the same. Figure 8b shows the upstream delay of VI (T2). At lower load, both of the wireless modes are almost linear, but as the load increases, the US-delay for DCF increases exponentially because of the non-priority-based FIFO queueing mechanism of traffic; however, the US delay of VI (T2) remains lower in EDCA mode due to the high-priority traffic queuing mechanism and HCF algorithm. Almost similar behavior is seen for the US delay of BK (T3), where again, EDCA performs better than DCF wireless mode at higher traffic loads. However, the performance of BE (T4) is different than the VO (T1), VI (T2), and BK (T3) traffic classes, as evident from Figure 8d. The US delay of BE (T4)-DCF is lower at lower traffic load but it increases as traffic load increases. This happens due to the least priority of BE traffic in EDCA but due to efficient mapping of the HCF algorithm and increased queuing delays in DCF mode at higher loads. Overall, EDCA mode shows up to 93.2%, 97.5%, 97.6%, and 93.8% lower US delays compared to DCF mode for VO (T1), VI (T2), BK (T3), and BE (T4) traffic. Figure 9 shows the comparative results of overall mean US delay of all traffic classes for our proposed work and earlier work [25] (we call it dGIANT) that did not use the HCF algorithm for traffic mapping and only relied on GIANT DBA. It is clearly evident from Figure 9 that the overall US mean delay of dGIANT DBA is higher compared to our work for both wireless techniques: EDCA and DCF. Initially, the delay in case of DCF of both DBA schemes is lesser, however, it increases as the traffic load increases, due to the same reasons described above. Overall, HCF-DBA shows up to 54.8% and 53.4% lower delays for DCF and EDCA modes compared to the dGIANT scheme. Figure 8: US delay VS traffic load in the FiWi access network: (**a**) Voice traffic case, (**b**) video traffic case, (**c**) background traffic case, and (**d**) best effort traffic case. The fairness performance, using the Jain's Fairness Index (JFI), of the proposed scheme was also performed and compared with the dGIANT scheme. The JFI value, termed as \(f(y)\), ranges from 0 to 1, and a higher value implies a tighter relationship between allocated bandwidth and overall allocation, showing a better QoS.