# Highest Cost First-Based QoS Mapping Scheme for Fiber Wireless Architecture
## 2 Related Work  
In the literature, the wireless-fiber integration technology has been implemented with different wireless technologies, such as WiMax, WLAN, and Long Term Evolution (LTE). However, the key requirement of any of the implementation is to guarantee the QoS. In most of the studies, a standalone architecture comprising of Ethernet Passive Optical Network (EPON) and WiMAX has remained in focus. For example, the study in Reference [17] introduced the policy of minimum best effort (MBE), where all services are granted the minimum bandwidth. The dynamic allocation takes into account QoS and traffic arrival rates and treats the bandwidth requests using a real-time polling service/assured forwarding (PS/AF) policy. In another similar study, the authors of Reference [18] demonstrated a new generation broadband network and proposed four integrated architectures based on the integration of WiMAX and EPON to reduce operational costs in a fixed-mobile converged (FMC) network. An integrated WiMAX-EPON network approach for the same standalone architecture with extended coverage was demonstrated in Reference [19]. The proposed architecture uses an intermediate sub-network of OLTs between the normal configuration of OLT and ONUs. This sub-OLT handles the networking issues in the backhaul and the front-end. Using LTE capability to work with a high data rate, the convergence of EPON and LTE technologies have been implemented for possible FiWi networks [20]. Another FiWi network has been designed with a combination of wireless sensor networks (WSNs) and EPON, known as fiber wireless sensor network (Fi-WSN) [21]. This cross-layer service mechanism is designed to reduce processing delay at ONUs for smart grid applications. Researchers envisage the use of different GPON DBA algorithms in the context of XGPON fiber to the antenna, where the fiber optic terminates at the base station of the LTE network as backhaul, and they have also proposed a deficit XGIANT DBA for the XGPON network [22]. A testbed was designed for an integrated GPON-WiMAX architecture, where GPON was used as a backhaul with WiMAX as a front-haul [23]. They designed a mapping among the traffic classes of GPON and traffic class of the WiMAX network according to the respective QoS standards. The study in Reference [24] presented the QoS mapping policy for the pairs of ONU-evolved Node-B (ONU-eNB) for LTE/EPON networks. In this policy, each LTE packet was stamped with the inimitable Differentiated Services Code Point (DSCP) values and then sent to ONU. A single FIFO queue performs all to one mapping and each DSCP is set for the class of service (CoS) to ensure an easy QoS mapping for the ONU-eNB ONU. This DSCP-to-CoS preset takes the place of packet classification in the ONU, encouraging the minimal loading of the packet classification. A QoS-aware integration of the XG-PON and Wi-Fi network was designed in Reference [25] to provide e-services to subscribers. Authors have used the DXGIANT DBA algorithm at the XGPON side and the EDCA model at wireless local area network with IEEE 802.11n. IEEE 802.11n is the 4G Wi-Fi standard [26]. They observed that the low-priority traffic suffered from bandwidth starvation, making the network unfair for the best-effort traffic due to a high transmission opportunity (TXOP) period and contention window (CW) time in EDCA. Therefore, they focused on modification of the TXOP and the CW parameters. They claimed that they achieved more fairness for low-priority traffic in their FiWi scenario. A hierarchical QoS-aware DBA (HQA-DBA) algorithm has been proposed for the surplus sharing policy in Reference [27]. The proposed DBA algorithm supports the fairness of bandwidth for assigning bandwidth to users according to its QoS requirements and based on priority queue weight. The authors proposed two DBA schemes that run separately in OLT and OBF (ONU-BS facility). Both DBA algorithms are responsible for the appropriate allocation of bandwidth in their respective domain.