While the problems of spectrum sensing and sharing at the physical and link layers have received a lot of attention within the research community, end-to-end data delivery at the upper layers of the protocol stack remains a completely unexplored problem. This projects aims to design a transport layer for CR ad hoc networks and analyze its operation, so that can the source can effectively interpret congestion events, spectrum-related outages, fluctuations in bandwidth availability, and intermittent spectrum sensing induced interruptions, on the end-to-end data delivery.

Our proposed work will advance the design and analysis of the CR transport layer through the following aims:

1. We will analyze various flavors of TCP, such as Reno, New Reno, Vegas to identify which of these are best suited, in their current standardized implementations, to meet the challenges of dynamic spectrum access. This will yield comprehensive insights on the best practices for future transport layer design.
2. We will explore the extent of cross-layer information, such as knowledge of when, where and for how long a primary user (PU) affects the connection, on typical window-based congestion control methods, such as the additive-increase-multiplicative-decrease mechanism in TCP. This will advance the science of effectively integrating and prioritizing information from the lower-layers and other nodes in the chain, whenever obtaining this information is feasible.
3. We will research new directions on equation-based congestion control for CR, which breaks free from the self-clocking mechanism of TCP, and allows for near-instantaneous response to changing spectrum conditions.

Personnel:
Fan Zhou

Publications:
Journals and Magazines

• R. Doost-Mohammady, M. Y. Naderi, and K. R. Chowdhury, “Performance Analysis of CSMA/CA based Medium Access in Full-Duplex Wireless Communications,” IEEE Transactions on Mobile Computing, vol. 15, no. 6, Jun. 2016.
• A. Al-Ali, Y. Sun, M. DiFelice, J. Paavola and K. R. Chowdhury, “Accessing Spectrum Databases using Interference Alignment in Vehicular Cognitive Radio Networks,” IEEE Transactions on Vehicular Technology, vol. 64, no. 1, Jan 2015.
• Y. Sun and K. R. Chowdhury, “Enabling Emergency Communication through Cognitive Radio Vehicular Network,” IEEE Communications, vol. 52, no. 10, Oct. 2014.

Conferences and Workshops

• W. Lei, F. Zhou, W. Meleis, and K. R. Chowdhury, “Learning-based and Data-driven TCP Design for Memory-constrained IoT,” IEEE DCOSS, Washington D.C., 2016.
• F. Zhou, K. R. Chowdhury and D. Choffnes, “Janus: Network and Application-aware Multi-TCP Optimization Engine,” IEEE INFOCOM, Poster Session, San Francisco, CA, USA, Apr. 2016.
• F. Zhou, A. Al-Ali and K. R Chowdhury, “TCP Protocols in Dynamically Varying Bandwidth Conditions,” CROWNCOM, Doha, Qatar, April 2015.
• A. Al-Ali and K. R. Chowdhury, “Simulating Dynamic Spectrum Access using ns-3 for Wireless Networks in Smart Environments,” IEEE SECON Workshop on Self-Organizing Wireless Access Networks for Smart City, Singapore, June 2014.