# An Energy-Efficient Coverage Algorithm for Macrocell--Small Cell Network Systems
## 4 Proposed Algorithm
In order to operate efficiently, we have categorized all the possible scenarios for user \(i\) each time the algorithm is executed into three categories (i.e., Case 1, Case 2, and Case 3), based on the algorithmic methodology described in Figure 4. Take note that all of these scenarios are mutually exclusive. It should also be noted that the aforementioned mechanism for coping with situations in which there are coverage holes during the relay process will be automatically applied to these scenarios as necessary. The scenarios are described below:  
Case 1. The end point of user \(i\) will not fall within a coverage hole. 1. Service is provided at the starting point of user \(i\) in the SBS service state, and SBS service is also available at the end point. 1. The path process has SBSs providing support overlay. In this case (SSS), service is provided using the corresponding SBSs in the path process. An example is shown in Figure 5a. 2. The relay process does not have SBSs providing support overlay. However, the two SBSs that cover the starting and end points can be jointly used to provide relay process coverage after the adjustment of their power levels to \(P_{\text{s}}^{\text{(high)}}\), respectively. In this case (YNY), service is provided by these two cell-enlarged SBSs in the path process. An example is shown in Figure 5b. 3. The relay process does not have SBSs providing support overlay, and the relay process coverage cannot be compensated by the starting and end point SBSs after the adjustment of their power levels to \(P_{\text{s}}^{\text{(high)}}\), respectively. In this case (XNX), service is provided by switching to the MBS in the path process. An example is shown in Figure 5c. 4. Service is provided at the starting point of user \(i\) in the SBS service state, but SBS service is not available at the end point. 1. The relay process has SBSs providing support overlay, and coverage can include the end point after adjusting the power level of the SBS closest to the end point to \(P_{\text{s}}^{\text{(high)}}\). In this case (SYN), the cell of this SBS is enlarged, and service is provided using the corresponding SBSs in the path process. An example is shown in Figure 6a. 2. The relay process has SBSs providing support overlay, but coverage is unable to include the end point after adjusting the power level of the SBS closest to the end point to \(P_{\text{s}}^{\text{(high)}}\). In this case (SXN), the path process connection is switched to the MBS to provide service. An example is shown in Figure 6b. The relay process does not have SBSs providing support overlay. In this case (SNN), the path process connection is switched to the MBS to provide service. An example is shown in Figure 6c. * Service is provided at the starting point of user \(i\) in the MBS service state, and SBS service is available at the end point. * The relay process has SBSs providing support overlay, and coverage can include the starting point after adjusting the power level of the SBS closest to the starting point to \(P_{\mathrm{s}}^{\mathrm{(high)}}\). In this case (NYS), service is provided by transferring the original user-MBS connection at the starting point to this cell-enlarged SBS, with the corresponding SBSs being used in the remaining path process. An example is shown in Figure 7a. * The relay process has SBSs providing support overlay, but coverage is unable to include the starting point after adjusting the power level of the SBS closest to the starting point to \(P_{\mathrm{s}}^{\mathrm{(high)}}\). In this case (NXS), service is provided by using the MBS in the path process. An example is shown in Figure 7b. * The relay process does not have SBSs providing support overlay. In this case (NNS), service is provided by using the MBS in the path process. An example is shown in Figure 7c. * Service is provided at the starting point of user \(i\) in the MBS service state, but SBS service is not available at the end point.