# Renewable Energy-Based Energy-Efficient Off-Grid Base Stations for Heterogeneous Network
## 4 Results' Analysis
### Optimization Standard  
An optimal size of the components used for the proposed hybrid RES for the HetNet is summarized in Table 7. The proposed system is based on off-grid energy sharing and in terms of the consumed energy, the macro, and micro BSs will be served by solar PV and BG with battery storage and converter. Due to small energy requirements, pico and femto BSs will only be aided by solar PV and backup storage devices, and, as a consequence, no converter is needed to support the DC load. The proposed model has been simulated on the HOMER platform, taking the dynamic behavior of traffic and RES into account. It is recognized that a higher value of the component size is required for the bigger cell sizes due to the higher amount of energy consumption. With the change of system bandwidth,  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Value** \\ \hline \(\chi\) (Packet arrival rate) (M/G/1 stochastic process) & 0.05 to 0.5 packets/ms \\ \(\mu\) (Service rate) & 100 packets/ms \\ \(\tau_{CDRX}\) (known as \(T_{3324}\)) (eDRX long cycle timer length) & 5:2:35 \\ \(\tau_{\text{PSM}}\) (known as \(T_{3412}\)) (PSM sleep timer) & 3 h \\ \(\tau_{\text{t}}\) (lanctivity timer) & 10 ms \\ \(N\) (No of short cycles) & 1 to 16 \\ \(P_{Data}\) (Power consumption during ON period) & 500 mW \\ \(P_{Inactive}\) (Power consumption during inactivity timer) & 255 mW \\ \(P_{PDRX}\) (Power consumption during eDRX period) & 11 mW \\ \(P_{PSM}\) (Power consumption during deep sleep period) & 0.0108 \(\mu\)W \\ \hline \hline \end{tabular}
\end{table}
Table 6: Simulation parameters for Algorithm 2.  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Value** \\ \hline Resource block (RB) bandwidth & 180 kHz \\ System bandwidth, BW & 5, 10, 15, 20 MHz \\ Carrier frequency, \(f_{c}\) & 2 GHz \\ Duplex mode & FFD \\ Cell radius & 1000 m (macro), 500 m (micro), 200 m (pico), 10 m (femto) \\ BS Transmission power & 20 W (macro), 6.3 W (micro), 0.13 W (pico), 0.05 W (femto) \\ Noise power density & \(-174\,\text{dBm}/\text{Hz}\) \\ Path loss exponent, \(\alpha\) & 3.574 \\ Shadow fading \(X_{\sigma}\) & 8 dB \\ Access technique, DL & OFDMA \\ Traffic distribution & Randomly distributed \\ \hline \hline \end{tabular}
\end{table}
Table 4: Key parameters for MATLAB-based Monte-Carlo simulation setup [68].  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Value** \\ \hline \(\chi\) (Packet arrival rate) (M/G/1 stochastic process) & 0.05 to 0.5 packets/ms \\ \(\mu\) (Service rate) & 100 packets/ms \\ \(\tau_{\text{S}}\) (Short cycle timer length) & 20 ms \\ \(\tau_{L}\) (Long cycle timer length) & 320 ms \\ \(\tau_{st}\) (Step size timer) & 20 ms \\ \(\tau_{t}\) (Inactivity timer) & 10 ms \\ \(N\) (No of short cycles) & 1 to 16 \\ \(P_{Data}\) (Power consumption during ON period) & 500 mW \\ \(P_{Tast}\) (Power consumption during inactivity timer) & 255 mW \\ \(P_{OFF}\) (Power consumption during DRX period) & 11 mW \\ \hline \hline \end{tabular}
\end{table}
Table 5: Simulation parameters for Algorithm 1.  
the optimal size of the BG, battery units, and converters are remaining unchanged. On the other hand, the optimal size of the solar PV increase with the increment of system BW for both macro and micro BS configurations to cope up with the higher energy demand. As such, the proposed system is compatible under dissimilar BS network requirements.