Collaborative Research: Delay and Energy: Design Tradeoffs in Spectrally Efficient Systems

随着通信向电池容量有限的移动设备的过渡，能源消耗变得越来越重要。同时，由于需要支持时间敏感业务（如视频）的激增，需要仔细控制数据传输延迟。从用户的角度来看，这些是影响手机体验的主要因素：能量消耗（电池持续多长时间），延迟（等待内容的时间）。从社会的角度来看，无线通信对全球能源消耗和二氧化碳排放做出了重大贡献。据估计，目前全球二氧化碳排放量的0.5-1%是由无线通信直接造成的，与空中交通（2%）相当。与此同时，共享无线媒体的设备数量正在急剧增加。然而，在拥塞系统中，低延迟和低能耗是相互冲突的。因此，为了设计未来的通信系统，有必要了解拥塞系统中能量和延迟之间的基本权衡。这一基础分析的见解将用于联合设计新的通信软件和节能通信硬件，并将在无线测试台上进行测试。这种硬件可以作为未来无线通信设备的基础。该项目将涉及代表性不足的少数民族，包括夏威夷原住民，以鼓励这些少数民族参与STEM领域的本科研究经历。该项目旨在了解影响能量和延迟的因素，如待传输数据的时间特性和信道特性。为了获得对这些因素的基本理解，有必要分析信息理论背后的延迟和能量，考虑到系统的现实特征，包括网络和硬件。该项目建立在最近关于有限块长度通信的信息论工作的基础上。基本上，在传统信息论中，如果块长度是无限的，那么延迟也是无限的。因此，为了对延迟有更基本的理解，需要进行有限块长度分析。然而，块长度并不是延迟的直接指标。因此，有限块长度理论必须专门用于研究延迟和能量。初步结果表明，延迟对能量消耗的影响远远大于带宽限制对能量消耗的影响。本项目分四个步骤研究延迟和能量之间的权衡。首先发展了延迟和能量的基本信息理论。然后将其应用于多用户系统，其中频谱效率至关重要。在下一步中，它使用现实的硬件约束扩展模型。在最后一步，该理论在硬件测试台上进行了最先进的编码测试。该奖项反映了美国国家科学基金会的法定使命，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。

Energy consumption has become of increasing importance by the transition in communications to mobile devices with limited battery capacity. At the same time, data transmission delay needs to be carefully controlled due to the need to support the proliferation of time-sensitive services, such as video. Seen from a user perspective, these are the main things that affect the mobile experience: energy consumption (how long does the battery last), delay (how long to wait for content). From a societal perspective, wireless communications contribute significantly to global energy consumption and carbon dioxide emissions. An estimate is that currently 0.5-1% of global carbon dioxide emissions is due directly to wireless communications, comparable to that of air traffic (2%). At the same time, the number of devices that share the wireless medium is increasing dramatically. Yet, the desire for low delay and low energy consumption in congested systems conflict. In order to design future communication systems, it is therefore necessary to understand the fundamental tradeoff between energy and delay in congested systems. The insights from this fundamental analysis will be used to jointly design new communications software and energy efficient communication hardware, which will be tested in a wireless testbed. This hardware can be used as a basis for future wireless communication devices. The project will involve underrepresented minorities, including native Hawaiians, in undergraduate research experiences to encourage the participation of these minorities in the STEM field.The project aims to understand the factors that influence energy and delay such as the time characteristics of data to be transmitted and the characteristics of the channel. To obtain a fundamental understanding of these factors, it is necessary to analyze the information theory underlying delay and energy, taking into account realistic features of the systems, including networking and hardware. The project builds on the recent line of work in information theory on finite block length communications. Basically, if the block length is infinite, as in traditional information theory, the delay is also infinite. Therefore, in order to reach a more fundamental understanding of delay, finite block length analysis is needed. However, block length is not a direct indicator of delay. Therefore, finite block length theory has to be developed specifically for investigating delay and energy. Preliminary results show that delay affects energy consumption much more strongly than one would expect from bandwidth constraints alone. This project studies the tradeoff between delay and energy in four steps. First it develops the basic information theory relating delay and energy. It then applies this to multiuser systems, where spectral efficiency is essential. In the next step, it extends the models with realistic hardware constraints. In the final step, the theory is tested on a hardware testbed with state-of-the-art coding.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.