# Data-Driven Construction of User Utility Functions from Radio Connection Traces in LTE
## 5 Performance Assessment
### Results  
Figure 2 shows the analysis for full-buffer data services. Each point in the figure represents a connection labeled as full-buffer data service. The solid line represents the median connection duration, \(CD_{median}^{(f)}\), and the dashed line represents the median DL data volume, \(V_{DL_{median}}^{(f)}\). The throughput axis is adjusted to low values (below 10 Mbps) to better identify the boundary between the two states specified in Figure 1a. The results confirm the expected impact of user behavior, since, for a low DL PDCP throughput, the DL data volume decreases and the connection duration stagnates. The minimum QoS threshold can be determined as the \(TH_{PDCP,DL}^{(f)}\) value that causes \(CD_{median}^{(f)}\) to drop and \(V_{DL_{median}}^{(f)}\) to remain constant. From the figure, the estimated threshold for this service is \(TH_{PDCP,DL_{min}}^{(f)}=5\) Mbps.  
Figure 2: Quality of Service (QoS) and traffic indicators for full-buffer data services.  
Figure 3 shows the analysis pf streaming services. Each point in the figure represents a connection identified as a streaming service. The solid line represents the median DL session throughput, \(TH_{session,DL_{median}}^{(str)}\). Results show that \(TH_{session,DL}^{(str)}\) presents a trend close to the expected behavior in Figure 1b. Thus, the minimum QoE threshold for this service can be set as the \(TH_{PDCP,DL}^{(str)}\) value such that \(TH_{session,DL}\) reaches its peak; i.e., \(TH_{PDCP,DL,min}^{(str)}\) = 30 Mbps.  
Figure 4 shows the analysis of VoLTE. Each point in the figure represents a VoLTE connection. The solid line representing \(CD_{median}^{(v)}\) confirms the impact of users anticipated in Figure 1c. From the figure, it is inferred that the maximum DL packet delay threshold is \(\tau_{max}^{(v)}=20\) ms.  
Figure 5 shows the analysis of web browsing for webs with large objects. Each point in the figure represents a connection labeled as web browsing with this feature. The solid line represents \(CD_{median}^{(wl)}\), and the dashed line represents \(V_{DL_{median}}^{(wl)}\). A priori, user behavior for  
Figure 4: QoS and traffic indicators for a Voice over LTE (VoLTE) service.  
Figure 3: QoS and traffic indicators for streaming services.  
these services should be close to that in full-buffer services. However, the DL data volume seems not to be greatly affected by changes in DL PDCP throughput. This is due to the fact that web sessions manage a lower amount of data for each connection than full-buffer data services and thus the link performance must be much worse for the user to notice this degradation. Based on the available data, a minimum QoS value for this service cannot be obtained.  
Finally, Figure 6 shows the analysis of web browsing with small objects and social networks. Each point in the figure represents a connection identified as these services. The solid line represents \(CD_{median}^{(\text{ns})}\) and the dashed line represents \(V_{DL_{median}}^{(\text{ns})}\). It is observed that \(CD_{median}^{(\text{ns})}\) and \(V_{DL_{median}}^{(\text{ns})}\) do not show changes regardless of throughput values. This is due to the fact that these services manage a very small amount of data for each connection. As a consequence, user satisfaction relies more on successful data transactions rather than on the connection duration. Thus, only extremely bad link conditions would impact \(CD\). Thus, \(TH_{PDCP,DL,min}^{(\text{ns})}\) cannot be estimated.  
Figure 5: QoS and traffic indicators for a web browsing service (large objects).  
Figure 6: QoS and traffic indicators for social networks and web browsing services (small objects).