# 5G/B5G mmWave Cellular Networks with MEC Prefetching Based on User Context Information +
## 4 Computer Simulation  
### Simulation Condition and Performance Metric  
We evaluated the performance of the mmWave Edge Cloud system through numerical simulation. Table 4 lists the simulation parameters. The macro-cell BS and the small-cell BS conform to the standard specifications of 3 GPP (2.1 and 28 GHz) and IEEE802.11 ad (60 GHz). The installation of the 60 GHz band is positioned as a performance evaluation for future B5G cellular networks, such as NR-U. The BS antenna beam pattern follows the 3 GPP and IEEE802.11 specifications [34; 38]. Channel model is based on the quasi deterministic radio channel generator (QuaDRiGa) [39], which provides detailed representation of spatial correlation characteristics in a MIMO channel. Line-of-sight (LOS) component varies with the distance between the BS and the UE. It is modeled as a stochastic component in macro [38] and small cells [40], respectively. For user association, we apply the multi-band cell association method presented in [41]. The system rate, \(R\), combining the transmission rates of macro and small cells, is defined as follows.  
\[R=E\Bigg{[}\sum_{\text{M}=1}^{\text{J}_{\text{M}}}\sum_{u\in\mathcal{M}_{ \text{M}}}\min\left(\frac{W_{\text{M}}C_{u,j_{\text{M}}}}{|\mathcal{M}_{\text {J}_{\text{M}}}|},\frac{L_{u}^{\text{rem}}}{T_{\text{s}}}\right)+\sum_{s=1}^{ N_{\text{S}}}\sum_{j_{\text{S}}=1}^{J_{\text{S}}}\sum_{u\in\mathcal{S}_{s,j_{ \text{S}}}}\min\left(\frac{W_{\text{S}}C_{u,j_{\text{S}}}}{|\mathcal{S}_{s,j_{ \text{S}}}|},\frac{D_{u,s}^{\text{rem}}}{T_{\text{s}}}\right)\Bigg{]}, \tag{4}\]  
where \(W_{\text{M}}\) and \(W_{\text{S}}\) denote the available bandwidth at macro cells and small cells, respectively. \(C_{u,j_{\text{M}}}\) and \(C_{u,s,j_{\text{S}}}\) are the link capacity for the \(u\)-th UE and \(s\)-th small cell. \(T_{s}\) is the time slot. \(L_{u}^{\text{rem}}\) is the instantaneous remaining traffic demand of the \(u\)-th UE. \(N_{\text{s}}\) is the total number of small-cell BSs. \(J_{\text{M}}\) and \(J_{\text{S}}\) are the number of sectors at macro cell BS and small-cell BS. \(\mathcal{M}_{j_{\text{M}}}\) is the set of users belonging to a sector \(j_{\text{M}}\) of macro cell BS, and \(\mathcal{S}_{s,j_{\text{S}}}\) is the set of UE belonging to a sector \(j_{\text{S}}\) of small-cell BS \(s\). \(D_{u,s}^{\text{rem}}\) is the data stored in storage for the \(u\)-th UE and the \(s\)-th small cell, which is expressed in detail as:  
\[D_{u,s}^{\text{rem}}=\min(C_{\text{B}}T_{u,s},L_{u}^{\text{rem}}), \tag{5}\]  
where \(T_{u,s}\) is the total time slot for the \(u\)-th UE at the \(s\)-th small cell determined by the proposed prefetching algorithm--namely, mmWave high-speed access is released from low backhaul limitation \(C_{\text{B}}\) and accordingly the system rate, \(R\), can be improved due to the prefetching. On the contrary, if the total time slot \(T_{u,s}\) is small, mmWave access cannot demonstrate its capability due to the bottleneck of low backhaul capacity.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values** \\ \hline Bandwidth (Macro/Small) & 10 MHz/400 MHz/2.16 GHz \\ Carrier freq. (Macro/Small) & 2.1 GHz/28 GHz/60 GHz \\ Number of BS (Macro/Small) & 7 (1 for target)/84 (12 for target) \\ Number of BS sectors (Macro/Small) & 3/3 \\ BS antenna elements (Macro/Small) & 4/128 \\ \hline \hline \end{tabular}
\end{table}
Table 4: The simulation parameters.  
Figure 7: Illustration of traffic generation.