# Crowdsourcing Framework for QoE-Aware SD-WAN +
## 4 Proposed Framework  
### QoE Crowdsourcing  
The proposed framework uses real-time QoE crowdsourcing feedback of quality degradation during live video streaming over a cloud-based SD-WAN environment. Figure 4 highlights details of our framework, in which a streaming server transmits multimedia content over the SD-WAN environment. During the video streaming, dynamic network conditions and events may affect the perceived quality at the user end. Several streaming protocols can be considered such as RTP, SCTP, TCP, and UDP for data transmission. The SD-WAN is responsible for routing the video stream and delivering it to the participating users. A QoE-rating application is deployed on the user-end devices to return user feedback  
Figure 3: Real-time QoE content-based network model. during a real-time streaming, through which the participants click on a dislike button when they feel the quality has been degraded. The QoE-rating feedback application is designed to send REST API requests (if needed, these can be summarized through intermediate servers for scalability) to the SDN controller to inform the controller about potential problems in the current video stream and possibly request corrective actions such as traffic rerouting. The QoE rating application can be deployed as a plugin on web browsers, as a plugin on multimedia players, or as a desktop application. In contrast to the MOS technique, participants do not have to decide between different grading scales; instead, they only alert the SD-WAN controller to quality degradation, thus providing more decisive feedback. The timing between feedbacks could be an indication of quality, i.e., more frequent feedback (\"dislike\" clicks) indicates a lower quality than less frequent feedback. As such, all clicks are timestamped before transmission. The intermediate servers can collect this feedback and provide summaries (e.g., number of dislikes within a given time interval) to the QoE-control algorithm on the SD-WAN controller for potential actions. Providing crowd-based QoE feedback would enable the SD-WAN controller to detect problems in the service path and to take corrective action by making changes to the virtual topology of the content delivery network, reassigning users, or rerouting traffic. Ideally, a resource optimization algorithm such as [27] can be executed in real time to respond to QoE degradation; however, the complexity and processing time of such algorithms must be considered in order to provide an effective remedy in real time. The use of crowdsourcing would provide a more scalable and efficient method for collecting feedback, whether to correct real-time problems or to create performance benchmarks. The SD-WAN QoE-aware rerouting mechanism operates as follows:  
1. The transport route on SD-WAN experiences delay or loss on specific network links, causing quality degradation in delivery and resulting in delay, jitter, or loss. 2. When the users notice the video quality degradation, they click the 'Dislike' button. The feedback is transmitted to the feedback server through HTTP. Figure 4: Real-Time QoE crowdsourcing feedback based on SD-WAN environment. The server communicates the feedback to the SDN controller  
The controller resolves client and server IPs into MACs using REST. The controller retrieve current intent information  
The controller queries current traffic path. The controller computes alternative paths between client and server  
The controller installs the modified intent and query new path. A new streaming path is established and QoE enhancement is verified through user feedback (i.e., lack of dislike feedback). A high-level description of the QoE feedback collection and evaluation applications on the client and server sides is presented in the following Box 1. More implementation details, including controller operations, are described in Section 5.