NeTS: Small: Low Latency Uplink Communications in Low Earth Orbit (LEO) Satellite Networks with Chirp Permutation Multiple Access (CPMA)

在这个项目中，Chirp置换多址接入（CPMA），这是一种新的无线通信技术，低地球轨道（LEO）卫星网络，旨在实现最小的通信延迟上的上行链路从用户终端到卫星。低地球轨道卫星网络已成为补充现有无线基础设施的一个强有力的选择，特别是在向农村地区和海洋等传统上难以到达的地区提供宽带数据服务方面。CPMA解决了LEO卫星网络的关键挑战之一，即通信延迟，并将支持对延迟高度敏感的应用，如自动驾驶和游戏。CPMA通过将延迟减少到从用户终端到卫星的单向传播延迟来最小化延迟，因为CPMA允许用户终端在任何时间发送分组，而无需彼此协调或等待关于资源分配的决定。通过实现新的应用，CPMA将造福社会，提高生活质量。该项目将促进对无线网络中免授权通信的认识和理解。该项目的成果将与教育相结合，例如用于课程项目。CPMA的主要新奇之处在于它的物理层，它允许卫星解码来自多个用户终端的重叠数据包，并通过上行链路实现免授权通信。CPMA通过变换线性调频脉冲波形来调制数据，线性调频脉冲波形是具有恒定幅度和线性增加频率的复矢量。密钥变换是对线性调频信号的置换，可以有效地降低分组间干扰的影响。在这个项目中，CPMA的物理层和链路层都将被设计、实现和测试。物理层将通过具有已证明的保证的排列和多种类型的啁啾变换来优化。链路层将充分利用物理层的能力，并基于来自彼此接近的多个用户终端的集体反馈来解决诸如高效分组重传和传输功率控制之类的问题。理论分析将揭示网络容量，并证明设计的最优性。CPMA有望实现超低延迟、高数据速率和高网络容量。CPMA将在USRP上实施，并在开放平台（如POWDER）上进行演示，并通过由通道轨迹和广泛接受的通道模型驱动的模拟进行评估。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project, Chirp Permutation Multiple Access (CPMA) is proposed, which is a novel wireless communication technology for Low-Earth-Orbit (LEO) satellite networks aiming at achieving minimum communication latency on the uplink from the user terminals to the satellite. LEO satellite networks have emerged as a strong option to complement the existing wireless infrastructure, especially for providing broadband data services to areas that are traditionally difficult to reach, such as rural areas and oceans. CPMA addresses one of the key challenges in LEO satellite networks, namely, the communication latency, and will enable applications that are highly sensitive to latency, such as automatic driving and gaming. CPMA minimizes latency by reducing it to the one-way propagation delay from the user terminal to the satellite, because CPMA allows user terminals to transmit packets at any time without coordinating with each other or waiting for decisions on resource allocations. By enabling novel applications, CPMA will benefit society and improve quality of life. This project will advance the knowledge and understanding on grant-free communications in wireless networks. Results from this project will be integrated with education, such as used in course projects. Undergraduate students and students from underrepresented and minority groups will be actively recruited.The key novelty of CPMA is its physical layer, which allows the satellite to decode overlapping packets from multiple user terminals and enables grant-free communications over the uplink. The CPMA modulates data by transforming the chirp waveform, which is a complex vector with constant magnitude and linearly increasing frequency. The key transformation is the permutation of the chirp, which can effectively reduce the impact of interference across packets. In this project, both the physical layer and the link layer of CPMA will be designed, implemented, and tested. The physical layer will be optimized with permutations with proven guarantees and multiple types of transformations of the chirp. The link layer will fully harness the capabilities of the physical layer and solve problems such as efficient packet retransmission and transmission power control based on collective feedback from multiple user terminals close to each other. Theoretical analysis will be conducted to reveal the network capacity and prove the optimality of the design. CPMA is expected to achieve ultra-low latency, high data rate, and high network capacity. CPMA will be implemented on USRPs and demonstrated in open platforms such as POWDER, as well as evaluated with simulations driven by channel traces and widely accepted channel models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.