CIF: Small: Fundamental Communication Latency Limits Beyond the Traditional Block-Coding Architecture

Last updated in September 2023.

Project Team

· Principal Investigator: Chih-Chun Wang (Purdue).

Vision

Advanced wireless communication networks have continuously been a major driving force behind technological innovations that transform modern society. A few prominent such examples include the unparalleled convenience of smartphones, personalized and widely adopted health monitoring devices, and smart soil / crop sensors for precision agriculture. While the amount of data that can be delivered wirelessly has increased exponentially in the past decades through numerous innovations of signal processing, there is significantly less progress on the reduction of latency (i.e. response time) of wireless communications. This project aims to substantially shorten the wireless communication latency by first characterizing the drawbacks of the ubiquitously used design paradigm called the block coding architecture. The project will then design non-block-coding-based solutions that significantly lower the latency beyond what is considered possible under the industry-standard block-coding architecture. The new ultra-fast response time of wireless communications will support complex, diverse, and highly dynamic applications in Internet-of-Things, edge computing, and cyber-physical systems, and is likely to unlock countless new transformative applications beyond what is conceivable under today's technologies.

In the relentless pursuit of ultra-low latency, a system designer must utilize every source of delay reduction, and this project thus takes a multi-pronged approach that minimizes, simultaneously, the decode-&-forward delay in the network level, the queueing delay in the link level, and the synchronization delay in the signal level. For the network level, the project will reinvent amplify-&-forward schemes by designing a soliton-based concatenation mechanism that takes advantage of the ultra-low latency of amplify-&-forward without its main drawback of error accumulation. For the link level, new random-walk-based analysis and design tools will be developed as the theoretical foundation for new blockless designs that eliminate queueing delay completely through continuous, on-the-fly packet encoding. For the signal-level, this project proposes a rateless design under the framework of quickest change detection. The resulting scheme would significantly improve the link start-up / synchronization time, a major source of delay when sending short, sporadic messages to Internet-of-Things devices. The theoretical results of this project are aim to inspire new practical designs that harvest the ultra-low latency benefits beyond any block-based solutions and open up new ideas in other important disciplines, including reliable and fast information propagation over noisy social networks, and distributed computation over unreliable communication networks.

Key Accomplishments

We conducted research on the network level, the link level and the signal level, respectively.

Network Level

· A new lossless Amplify-&-Forward design has been proposed, which achieves the optimal learning rate of sending 1-bit message over arbitrary acyclic networks, for which each constituent channels is of binary-input/symmetric-output.

Broader Impacts

The PI has continuously focused on disseminating the discovery of this project to international research communities, see the product section below.

Wang has continuously focused on training undergraduate students and GRAs through research activities, group seminars, and conference presentations. Wang, Love, and Krogmeier have continuously supervised a Purdue-VIP undergraduate research team since fall 2019, with weekly 90-min meetings dedicated to engaging undergraduate students in graduate-level research on wireless communications.

To further promote student engagement, the VIP teams of spring 2022, fall 2022, and spring 2023 participated in the poster presentation of Purdue Undergraduate Research Conference, an in-person event that have resumed on a semester-basis after the pandemic in 2020. For each semester, there are more than 300 student-led posters participating in-person for this university-wide event. Wang also served as one of the judges for the research talks competition consecutively from spring 2022 to spring 2023, which awarded the top 3 in-person research talks for each of the ten schools of Purdue University.

Products

Journal papers:

Conference papers:

· C.-C. Wang and D. Love, “Optimal Learning Rate of Sending One Bit Over Arbitrary Acyclic BISO-Channel Networks,” in Proceedings of the IEEE Int'l Symp. Information Theory (ISIT), Taipei, Taiwan, June 25-30, 2023.

· P.-W. Su, Y.-C. Huang, S.-C. Lin, I.-H. Wang, and C.-C. Wang, “Detailed Asymptotics of the Delay-Reliability Tradeoff of Random Linear Streaming Codes,” in Proceedings of the IEEE Int'l Symp. Information Theory (ISIT), Taipei, Taiwan, June 25-30, 2023.

The results in the NSF Public Access Repository will include a comprehensive listing of all journal publications recorded to date that are associated with this project.

Graduate Research Assistants & Collaborators

Graduate Research Assistants:

· Won Jun Lee;

· Giles Bischoff;

· Pin-Wen Su;

Other Collaborators:

· Jerry Huang (National Chiao-Tung Yang-Ming University, Taiwan)

· James Krogmeier (Purdue University, USA)

· Shih-Chun Lin (National Taiwan University, Taiwan)

· David Love (Purdue University, USA)

· I-Hsiang Wang (National Taiwan University, USA)