Inter-Cell Offloading with Capacity and Coverage Optimization in Heterogeneous Network

In heterogeneous network, it is important to bal-ance the traffic load between macro cells and smallcells. Traffic offloading can be made by controlling transmit power of each base station to resize its cell coverage. Raising transmit power of a base station can cause contradicting two effects: enhanced spectral efficiency within the cell and increased traffic demand coming from enlarged coverage. Thus, we proposed an inter-cell traffic offloading scheme by exploiting mechanism of capacity and coverage optimization in self organizing network. The simultaneous pursuit of capacity maximization and coverage provision is reflected in the algorithm by taking one measure, the bandwidth utilization. The system is assumed to be able to collect bandwidth utilization status of all cells to operate the algorithm in centralized manner. The proposed algorithm pursuits suboptimal solution for transmit powers of macrocells and smallcells by perturbing the transmit power vector intentionally to run a trial-and-error strategy. The system model largely follows conventional two tier wrap-around cellular network geometry with additional three small cells embedded in each macrocell. Under such geometry, macrocells and smallcells are designed to behave differently under different transmit power constrictions. A simulation has been conducted with specified system utility function and three thousands of iteration has been made to get a result well converged. The simulation results display successful traffic load rebalancing can be made by adjusting the transmit power of macrocells and smallcells with the proposed algorithm.