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，由于需要支持视频等时间敏感型服务的激增，因此需要仔细控制数据传输延迟。从用户的角度来看，这些是影响移动体验的主要因素：能耗(电池续航时间)、延迟(等待内容的时间)。从社会角度来看，无线通信对全球能源消耗和二氧化碳排放有很大贡献。据估计，目前全球二氧化碳排放量的0.5%-1%直接来自无线通信，与空中交通(2%)相当。与此同时，共享无线介质的设备数量也在急剧增加。然而，在拥挤的系统中，对低延迟和低能耗的渴望是相互冲突的。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时延之间的基本权衡。来自这一基本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，并将在无线试验台上进行测试。该硬件可以作为未来无线通信设备的基础。该项目将让未被充分代表的少数群体，包括夏威夷原住民，参加本科生的研究体验，以鼓励这些少数群体参与STEM领域。该项目旨在了解影响能量和延迟的因素，如要传输的数据的时间特性和通道的特性。为了从根本上了解这些因素，有必要分析延迟和能量背后的信息理论，并考虑到系统的现实特征，包括网络和硬件。该项目建立在有限块长度通信信息论的最新工作基础上。基本上，如果块长度是无限的，就像在传统信息论中那样，延迟也是无限的。因此，为了对时延有一个更基本的理解，需要对有限块长度进行分析。然而，数据块长度不是延迟的直接指示器。因此，必须专门发展有限块长度理论来研究延迟和能量。初步结果表明，延迟对能量消耗的影响比人们仅从带宽限制中预期的要大得多。本项目分四个步骤研究延迟和能量之间的权衡。首先，它发展了与延迟和能量相关的基本信息理论。然后，它将这一点应用于多用户系统，其中频谱效率至关重要。在下一步中，它使用真实的硬件约束来扩展模型。在最后一步，这一理论在硬件试验台上进行了测试，采用了最先进的编码。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.