# Key Quality Indicators Prediction for Web Browsing with Embedded Filter Feature Selection
## 2 Related Works
### KQI for OTT Web Browsing  
KQI is a collection of metrics which is utilized to characterize the quality of a service, usually based on the service characteristics and their relevance to the user experience. An OTT web browsing process generally consists of four steps: DNS resolution, TCP connection, HTTP page request and HTTP page response. Specifically, its KQIs are defined as follows [9](1) First packet delay (\(D_{k}\)): The time interval between a page request and the arrival of the first HTTP 200 OK packet. That is,  
\[D_{k}=T_{200}-T_{req} \tag{1}\]  
where \(T_{req}\) is the time when the user initiates a page request, and \(T_{200}\) is the time when the terminal receives the first 200 OK packet.  
The first packet delay can be further broken down into three sub-indicators, namely, \(D_{dns}\) (DNS resolution delay), \(D_{tcp}\) (TCP connection delay) and \(D_{get}\) (HTTP request delay):  
\[D_{k}=D_{dns}+D_{tcp}+D_{get} \tag{2}\]  
\[\left\{\begin{array}{l}D_{dns}=T_{dns}-T_{req}\\ D_{tcp}=T_{tcp}-T_{dns}\\ D_{get}=T_{200}-T_{tcp}\end{array}\right. \tag{3}\]  
where \(T_{dns}\) refers to the time when the terminal receives the DNS resolution result, and \(T_{tcp}\) is the time when the terminal sends a TCP connection confirmation.  
(2) Page open delay (\(D_{p}\)): The time duration since the user initiates the URL request until the whole page (text content only, excluding the resources in the page) is downloaded and rendered. The page open delay reflects the total time that the user needs to wait. It is defined as,  
\[D_{p}=D_{k}+D_{res} \tag{4}\]  
where \(D_{res}=T_{res}-T_{200}\) refers to the HTTP response delay. Here, \(T_{res}\) is the time when the terminal responds the [FIN, ACK] message.  
It should be noted that OTT web browsing on the phone is quite different from the traditional one on the PC side, specifically, they are as follows.  
1. Different service process and mechanism: In order to reduce unnecessary throughput consumption and improve user experience, both the browser and the web pages on the phone are tailored for screen size and resolution. The downloading and rendering mechanism, which is in general on-demand based, is also different from that of its PC counterpart.
2. Different factors that affect the service experience: With the whole mobile network getting involved, the factors that affect an OTT web browsing is much more complicated than that of the traditional web service. In particular, the fast-changing wireless environment has a great impact on the service experience, thus bringing challenges to the trouble shooting of service deterioration.
3. Different definition of the indicators: for example, the DNS resolution delay includes the delay of air interface setup, which is not considered in the PC web browsing.  
In addition to the KQIs, the network and the location information are also collected simultaneously. They are utilized to analyze and locate the service problems. The network information generally includes wireless ID and coverage parameters. For LTE network, for instance, the wireless ID refers to [tracking area code (TAC), eNodeB ID, cell ID (CI)], while the coverage parameters include Reference Signal Receiving Power (RSRP), Reference Signal Receiving Quality (RSRQ), and signal-to-interference and noise ratio (SINR).