## 2 Literature Review  
Different communication features, such as system capacity, throughput, spectral efficiency, and latency, are expected to be improved by applying the D2D communication techniques of 5G networks [6]. In [7], the focus was on optimizing the energy efficiency of a cellular network that incorporated D2D communication. The authors proposed a modified derivative algorithm and compared its performance with the original derivative algorithm using MATLAB simulations. The evaluation considered cellular density users and D2D density users in an uplink environment with multiple bands of the spectrum being shared by both the cellular and device users, each with a bandwidth of 25 MHz. The results showed that the modified derivative algorithm achieved an improved energy efficiency compared to the original algorithm. The simulations demonstrated a nearly ideal performance, indicating the suitability of the proposed algorithm for 5G applications. Additionally, the study suggested the possibility of determining the optimal D2D user and cellular density for each band and conducted trade-off analyses. Several resource allocation schemes have been proposed to improve the throughput, quality of service (QoS), and battery lifetime of systems operating in remote areas without grid power. However, previous attempts to achieve energy efficiency in such scenarios have often resulted in poor QoS, a limited bandwidth, and insufficient throughput. The authors in [8; 9; 10; 11; 12] showed that D2D communications underlying cellular networks can extend the device battery life compared to traditional cellular communication. However, the high energy consumption during transmission remains a challenge. In [13], the authors proposed a power-efficient discovery strategy and power allocation communication. Unfortunately, their method resulted in poor QoS due to the lack of near-to-near discovery methods between devices located on the same cellular network. Furthermore, the time taken for scheduling to transmit data between devices is very high. Though technologies such as \begin{table}
\begin{tabular}{l l} \hline \hline _Notation_ & _Definition_ \\ \hline _SINR_ & Signal to Interference and Noise to ratio \\ _QoS_ & Quality of Service \\ _K\({}_{D2D}\)_ & The fading coefficients of the D2D link \\ _SD2D_ & Smart bekekeeping device-to-device communication \\ \(a\) & Symbolizes the path-loss exponent \\ _AWGN_ & Additive white Gaussian noise \\ _T\({}_{o}\)_ & Variance \\ _CUE_ & Cellular user equipment \\ _DT_ & Data throughput \\ _TP_ & Transmitter power with amplifier inefficiency \\ _FP_ & Fixed circuit power \\ _PC_ & Power per transceiver chain \\ \(A\) & The coding/decoding/backhaul \\ \(B\) & Bandwidth of the line \\ \(K\) & Multiplexed users \\ _K\({}_{DR}\)_ & The link between the UE (D2D User Equipment) receiver and the Uth UE transmitter \\ _K\({}_{D2D}\)_ & The fading coefficients of the D2D link \\ _UE_ & User equipment \\ _B\({}_{DR}\)_ & The complex normal distribution \\ \(r\) & The D2D link that uses the channel g \\ \(\varphi_{g}(r)\) & Data rate \\ _Mcn_ & Transmit power of D2D Transmitter \\ _M\({}_{D}\)_ & Transmit power of cellular user equipment \\ _eNB_ & Evolved node B \\ _SCeNB_ & Small cell evolved node B \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Notation and abbreviations. wireless fidelity (WiFi) or Bluetooth provide some D2D communication functionality in the unlicensed band, the main challenge is that the interference becomes uncontrollable [14]. In addition, they cannot provide security and QoS guarantees as cellular networks can. However, different recent works on D2D communication integrated into cellular systems have reported issues in energy efficiency, QoS, and radio resource allocation, as well as in communication session setup and management procedures [15; 16]. In our proposed SBD2D communication application, energy efficiency is of the highest importance while exploiting the benefits of 5G and D2D communication.