Coverage optimization is a main challenge for small cell clusters which are considered to be a promising solution to provide seamless cellular coverage for large indoor or outdoor areas. This paper focuses on small cell cluster coverage problems and proposes both centralized and distributed self-optimization methods. Modified Particle swarm optimization(MPSO) is introduced to centralized optimization which employs particle swarm optimization(PSO) and introduces a heuristic power control scheme to accelerate the algorithm to search for the global optimum solution. Distributed coverage optimization is modeled as a non-cooperative game, with a utility function considering both throughput and interference. An iterative power control algorithm is then proposed using game theory(DGT) which converges to Nash Equilibrium(NE). Simulation results show that both MPSO and DGT have excellent performance in coverage optimization and outperform optimization using simulated annealing algorithm(SA), reaching higher coverage ratio and throughput while with less iterations. Coverage optimization is a main challenge for small cell clusters which are considered to be promising cells to for large indoor or outdoor areas. This paper focuses on small cell cluster coverage problems and proposes both centralized and distributed self-optimization methods. Modified Particle Swarm Optimization (MPSO) is introduced to centralized optimization which employs particle swarm optimization (PSO) and introduces a heuristic power control scheme to accelerate the algorithm to search for the global optimum solution. Distributed coverage optimization is modeled as a non-cooperative game , with a utility function considering both throughput and interference. An iterative power control algorithm is then proposed using game theory (DGT) which converges to Nash Equilibrium (NE). Simulation results show both both MPSO and DGT have excellent performance in coverage optimization and outperform optimization using simulated annealing algorithm (SA), re aching higher coverage ratio and throughput while with less iterations.