This paper presents a joint trajectory and communication design for multi-UAV enabled wireless networks. The goal is to maximize the minimum throughput among ground users by jointly optimizing user scheduling and association, UAV trajectory, and transmit power control. The formulated problem is a mixed integer non-convex optimization problem, which is challenging to solve. To address this, an efficient iterative algorithm is proposed using block coordinate descent and successive convex optimization techniques. The algorithm alternately optimizes user scheduling and association, UAV trajectory, and transmit power. For the non-convex UAV trajectory and transmit power optimization problems, two approximate convex optimization problems are solved. The proposed algorithm is guaranteed to converge. A low-complexity initialization scheme is also proposed for the UAV trajectory design based on the simple circular trajectory and the circle packing scheme. Extensive simulation results demonstrate the significant throughput gains of the proposed design compared to other benchmark schemes. The results show that the throughput of the proposed mobile UAV system increases with the UAV trajectory design period, revealing the fundamental throughput-access delay tradeoff in multi-UAV enabled communications. The proposed algorithm is shown to converge quickly and can be practically implemented with fast convergence for wireless networks of a moderate number of users. The paper also proposes a trajectory initialization scheme based on the simple circular trajectory and the circle packing scheme. The binary user scheduling and association solution is reconstructed based on the solution obtained for the relaxed problem. The results show that the proposed scheme can achieve higher accuracy and better performance by using a larger number of time slots without increasing the complexity. The numerical results demonstrate the effectiveness of the proposed algorithm in achieving significant throughput gains.This paper presents a joint trajectory and communication design for multi-UAV enabled wireless networks. The goal is to maximize the minimum throughput among ground users by jointly optimizing user scheduling and association, UAV trajectory, and transmit power control. The formulated problem is a mixed integer non-convex optimization problem, which is challenging to solve. To address this, an efficient iterative algorithm is proposed using block coordinate descent and successive convex optimization techniques. The algorithm alternately optimizes user scheduling and association, UAV trajectory, and transmit power. For the non-convex UAV trajectory and transmit power optimization problems, two approximate convex optimization problems are solved. The proposed algorithm is guaranteed to converge. A low-complexity initialization scheme is also proposed for the UAV trajectory design based on the simple circular trajectory and the circle packing scheme. Extensive simulation results demonstrate the significant throughput gains of the proposed design compared to other benchmark schemes. The results show that the throughput of the proposed mobile UAV system increases with the UAV trajectory design period, revealing the fundamental throughput-access delay tradeoff in multi-UAV enabled communications. The proposed algorithm is shown to converge quickly and can be practically implemented with fast convergence for wireless networks of a moderate number of users. The paper also proposes a trajectory initialization scheme based on the simple circular trajectory and the circle packing scheme. The binary user scheduling and association solution is reconstructed based on the solution obtained for the relaxed problem. The results show that the proposed scheme can achieve higher accuracy and better performance by using a larger number of time slots without increasing the complexity. The numerical results demonstrate the effectiveness of the proposed algorithm in achieving significant throughput gains.