In this paper, we propose a novel phased array with movable antennas (PAMA). By replacing traditional phase shifters with movable antennas, PAMA eliminates insertion loss of phase shifters and enhances antenna performance by leveraging the increased degrees of freedom in antenna positioning. We construct a periodic approximation-based beampattern synthesis (PABS) method. It leverages the approximate periodicity of the PAMA array response to obtain a high-quality initial solution through discrete optimization with quadruple-frequency sampling, which is subsequently refined using projected gradient descent. Simulations demonstrate the effectiveness of the proposed approach for multi-beampattern synthesis and highlight the impact of antenna movement range on synthesis performance. The results show that PAMA-based beampattern synthesis enhances beamforming accuracy and improves efficiency, especially in practical scenarios where digital phase shifters are used.

The increasingly complicated and diverse applications have distinct network performance demands, e.g., some desire high throughput while others require low latency. Traditional congestion controls (CC) have no perception of these demands. Consequently, literatures have explored the objective-specific algorithms, which are based on either offline training or online learning, to adapt to certain application demands. However, once generated, such algorithms are tailored to a specific performance objective function. Newly emerged performance demands in a changeable network environment require either expensive retraining (in the case of offline training), or manually redesigning a new objective function (in the case of online learning). To address this problem, we propose a novel architecture, DeepCC. It generates a CC agent that is generically applicable to a wide range of application requirements and network conditions. The key idea of DeepCC is to leverage both offline deep reinforcement learning and online fine-tuning. In the offline phase, instead of training towards a specific objective function, DeepCC trains its deep neural network model using multi-objective optimization. With the trained model, DeepCC offers near Pareto optimal policies w.r.t different user-specified trade-offs between throughput, delay, and loss rate without any redesigning or retraining. In addition, a quick online fine-tuning phase further helps DeepCC achieve the application-specific demands under dynamic network conditions. The simulation and real-world experiments show that DeepCC outperforms state-of-the-art schemes in a wide range of settings. DeepCC gains a higher target completion ratio of application requirements up to 67.4% than that of other schemes, even in an untrained environment.

Congestion control plays an important role in the Internet to handle real-world network traffic. It has been dominated by hand-crafted heuristics for decades. Recently, reinforcement learning shows great potentials to automatically learn optimal or near-optimal control policies to enhance the performance of congestion control. However, existing solutions train agents in either simulators or emulators, which cannot fully reflect the real-world environment and degrade the performance of network communication. In order to eliminate the performance degradation caused by training in the simulated environment, we first highlight the necessity and challenges to train a learningbased agent in real-world networks. Then we propose a framework, ARC, for learning congestion control policies in a real environment based on asynchronous execution and demonstrate its effectiveness in accelerating the training. We evaluate our scheme on the real testbed and compare it with state-of-the-art congestion control schemes. Experimental results demonstrate that our schemes can achieve higher throughput and lower latency in comparison with existing schemes.