# Intelligent Network Service Optimization in the Context of 5G/NFV
## 4 Methodology of MAPE's Analysis Service
### Opinion Model for Video Content Streaming  
MAPE's AS module is engineered to focus on optimizations related to streaming visual content using any device, from 5G-enabled mounted cameras to IoT wearables, UAVs, and UGVs, and this research aims to present and evaluate preliminary results for relevant field-originated video transmissions. According to ITU's model for video telephony applications [49], perceived video quality \(V_{q}\) is expressed, at a high level, as:  
\[V_{q}=1+I_{coding}\exp\left(-\frac{P_{plV}}{D_{P_{plV}}}\right) \tag{6}\]  
where \(I_{coding}\) denotes the basic video quality affected by the coding distortion, regarding a specific combination of video bit rate \(Br_{V}\) expressed in kilobits per second (kbps) and video frame rate \(Fr_{V}\) expressed in frames per second (fps). In addition, \(D_{P_{plV}}\) represents the degree of video quality robustness due to packet loss, whereas \(P_{plV}\) represents the packet loss rate. The video quality baseline affected by coding distortion \(I_{coding}\) is defined by:  
\[I_{coding}=I_{O_{fr}}\exp\left(-\frac{\left(ln(Fr_{V})-ln(O_{fr})\right)^{2}}{ 2D_{Fr_{V}}^{2}}\right) \tag{7}\]  
where \(O_{fr}\) represents the optimal frame rate that maximizes the video quality at each video bit rate and is expressed as:  
\[O_{fr}=v_{1}+v_{2}Br_{v} \begin{cases}1\leq O_{fr}\leq 30\\ v_{1},v_{2}:\text{\ constants}\end{cases}  \tag{8}\] \begin{table}
\begin{tabular}{c c c} \hline \hline
**Origin of Metric** & **Metric Name** & **Description** \\ \hline \multirow{3}{*}{OpenStack NFVI} & cpu\_util & The CPU’s utilization as a percentage \\  & memory\_util & The memory’s utilization as a percentage \\  & network.incoming.packets.rate & The rate of incoming packets \\  & network.outgoing.packets.rate & The rate of outgoing packets \\ \hline \multirow{3}{*}{Application} & frame\_rate & The frame rate of the video transmission \\  & bit\_rate & The bit rate of the video transmission \\  & packet\_loss & Network packet loss \\ \hline \multirow{7}{*}{collectd} & aggregation\_cpu-average\_user & The aggregated user CPU usage \\  & aggregation\_cpu-average\_system & The aggregated system CPU usage \\  & interface\_if\_octets\_rx & Count of bytes received on the interface \\  & interface\_if\_octets\_rx & Count of bytes transmitted by the interface \\  & interface\_if\_packets\_rx & Count of packets received on the interface \\  & interface\_if\_packets\_tx & Count of packets transmitted by the interface \\  & load\_load\_shorterm & The short-term load \\  & load\_load\_midterm & The mid-term load \\  & load\_load\_longterm & The long-term load \\  & memory\_percent\_free & The percentage of free memory \\  & memory\_percent\_used & The percentage of used memory \\  & processes\_fork\_rate & The fork rate of processes \\  & processes\_ps\_state\_running & Count of running processes \\  & processes\_ps\_state\_sleeping & Count of sleeping processes \\  & tcpconns\_tcp\_connections\_ESTABLISHED & Number of established TCP connections \\ \hline \multirow{2}{*}{QoE} & mean\_opinion\_score & The MOS value, denoting the \\  & quality of the transmitted content \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Employed monitoring metrics. \(I_{O_{fr}}\) is the maximum quality of a video for a constant bit rate, defined as:  
\[I_{O_{fr}}=v_{3}-\frac{v_{3}}{1+\left(\frac{Br_{V}}{v_{4}}\right)^{v_{5}}} \begin{cases} 0\leq I_{O_{fr}}\leq 4\\ v_{3},v_{4},v_{5}:constants\end{cases}  \tag{9}\]  
and \(D_{Fr_{V}}\) represents the degree of video quality robustness due to the frame rate, expressed as:  
\[D_{Fr_{V}}=v_{6}+v_{6}Br_{V} \begin{cases}0<D_{Fr_{V}}\\ v_{6},v_{7}:constants\end{cases}  \tag{10}\]  
Additionally, the packet loss robustness factor \(D_{P_{p_{p_{p_{p}}}}}\), which represents the degree of video quality robustness against packet loss, is given by:  
\[D_{P_{p_{p}}}=v_{10}+v_{11}\exp\left(-\frac{Fr_{V}}{v_{8}}\right)+v_{12}\exp \left(-\frac{Br_{V}}{v_{9}}\right) \begin{cases}0<D_{P_{p_{p}}}\\ v_{8},v_{9},\dots,v_{12}:constants\end{cases}