# Energy and Spectral Efficiency Balancing Algorithm for Energy Saving in LTE Downlinks
## 4 Performance Evaluation of the Proposed SET algorithm
### Impact of Varying Traffic Loads in Congested Network
#### 4.3.2 Impact of Varying Network Loads on a Congested Network Using a Directional Antenna  
A directional antenna that spreads radio signal in a specific direction called'sector', i.e., either 60\({}^{\circ}\) or 120\({}^{\circ}\) has been used in this scenario. In fact, transmitting or receiving radio signals in one direction or specific angle leads to a low level of interference, which consequently leads to improving the network capacity and coverage that in turn increase its successful delivery rate between UE and eNodeB/antenna.  
Moreover, Figure 16 shows how manipulating the number of UEs per eNodeB could improve the SE, where increasing the number of UEs increases the performance due to the competition. Since cell sectoring is performed by the proposed algorithm to enable radio signals to converge at a certain degree, thus, cell edge users are served with RBs because their channel state is in good condition. For this reason, the proposed algorithm exhibits a higher gain than the DRX power-saving algorithm due to its ability to rotate a directional antenna, which enables it to cope with the demands of cell edge users.  
In Figure 17, a comparison between the delay of the proposed SET algorithm and that of the DRX power-saving algorithm has been presented, where the latter has increased delay due to disregarding the packet delay requirements during RB allocation. The proposed algorithm was able to reduce the delay due to selecting the appropriate window size.  
Figure 16: SE as the number of UEs are increased in congested network for with directional antenna.  
Figure 15: SE-EE trade-off of congested network with omni-directional antenna.  
Moreover, the sectoring approach of a directional antenna considerably affects the delay metric due to the use of a reduced coverage area, however, the proposed algorithm was able to minimize the delay, which minimizes the interference. Meanwhile, the DRX algorithm increases the delay that significantly led to high energy consumption.  
The increase in the number of UE increases the amount of consumed energy due to the high interference, as shown in Figure 18. Consequently, the total performance is degraded when the energy consumption at eNodeB increases, which leads to a significant delay increase with both algorithms. However, the proposed algorithm still able to outperform the DRX power-saving algorithm due to its appropriate method to adjust the eNodeB to a certain degree.  
The impact of increasing the number of UEs in a congested network using a directional antenna by utilizing SET has been shown in Figure 19. This figure shows that the increase in SE always leads to EE increase. The proposed algorithm achieves its optimal point at 1.9 bit/s/Hz, which is higher than that of the DRX power-saving algorithm at  
Figure 17: Delay as the number of UEs are increased in congested network for with directional antenna.  
Figure 18: Energy consumption as the number of UEs are increased in congested network for with directional antenna.  
1.75 bit/s/Hz. This finding indicates that the proposed algorithm is able to outperform the DRX algorithm due to achieving its optimal value with lower energy consumption.