@article{hu_doshi_eun_2024, title={Minimizing File Transfer Time in Opportunistic Spectrum Access Model}, volume={23}, ISSN={["1558-0660"]}, url={https://doi.org/10.1109/TMC.2022.3212926}, DOI={10.1109/TMC.2022.3212926}, abstractNote={We study the file transfer problem in opportunistic spectrum access (OSA) model, which has been widely studied in throughput-oriented applications for max-throughput strategies and in delay-related works that commonly assume identical channel rates and fixed file sizes. Our work explicitly considers minimizing the file transfer time for a given file in a set of heterogeneous-rate Bernoulli channels, showing that max-throughput policy doesn't minimize file transfer time in general. We formulate a mathematical framework for static extend to dynamic policies by mapping our file transfer problem to a stochastic shortest path problem. We analyze the performance of our proposed static and dynamic optimal policies over the max-throughput policy. We propose a mixed-integer programming formulation as an efficient alternative way to obtain the dynamic optimal policy and show a huge reduction in computation time. Then, we propose a heuristic policy that takes into account the performance-complexity tradeoff and consider the online implementation with unknown channel parameters. Furthermore, we present numerical simulations to support our analytical results and discuss the effect of switching delay on different policies. Finally, we extend the file transfer problem to Markovian channels and demonstrate the impact of the correlation of each channel.}, number={1}, journal={IEEE TRANSACTIONS ON MOBILE COMPUTING}, author={Hu, Jie and Doshi, Vishwaraj and Eun, Do Young}, year={2024}, month={Jan}, pages={630–644} }
 @inproceedings{hu_doshi_eun_2021, title={Opportunistic Spectrum Access: Does Maximizing Throughput Minimize File Transfer Time?}, url={http://dx.doi.org/10.23919/wiopt52861.2021.9589243}, DOI={10.23919/wiopt52861.2021.9589243}, abstractNote={The Opportunistic Spectrum Access (OSA) model has been developed for the secondary users (SUs) to exploit the stochastic dynamics of licensed channels for file transfer in an opportunistic manner. Common approaches to design channel sensing strategies for throughput-oriented applications tend to maximize the long-term throughput, with the hope that it provides reduced file transfer time as well. In this paper, we show that this is not correct in general, especially for small files. Unlike prior delay-related works that seldom consider the heterogeneous channel rate and bursty incoming packets, our work explicitly considers minimizing the file transfer time of a single file consisting of multiple packets in a set of heterogeneous channels. We formulate a mathematical framework for the static policy, and extend to dynamic policy by mapping our file transfer problem to the stochastic shortest path problem. We analyze the performance of our proposed static optimal and dynamic optimal policies over the policy that maximizes long-term throughput. We then propose a heuristic policy that takes into account the performance-complexity tradeoff and an extension to online implementation with unknown channel parameters, and also present the regret bound for our online algorithm. We also present numerical simulations that reflect our analytical results.}, booktitle={2021 19th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)}, publisher={IEEE}, author={Hu, Jie and Doshi, Vishwaraj and Eun, Do Young}, year={2021}, month={Oct} }
 @article{cao_yin_hu_zhang_2020, title={Performance Analysis and Improvement on DSRC Application for V2V Communication}, DOI={10.1109/VTC2020-Fall49728.2020.9348743}, abstractNote={In this paper, we focus on the performance of vehicle-to-vehicle (V2V) communication adopting the Dedicated Short Range Communication (DSRC) application in periodic broadcast mode. An analytical model is studied and a fixed point method is used to analyze the packet delivery ratio (PDR) and mean delay based on the IEEE 802.11p standard in a fully connected network under the assumption of perfect PHY performance. With the characteristics of V2V communication, we develop the Semi-persistent Contention Density Control (SpCDC) scheme to improve the DSRC performance. We use Monte Carlo simulation to verify the results obtained by the analytical model. The simulation results show that the packet delivery ratio in SpCDC scheme increases more than 10% compared with IEEE 802.11p in heavy vehicle load scenarios. Meanwhile, the mean reception delay decreases more than 50%, which provides more reliable road safety.}, journal={2020 IEEE 92ND VEHICULAR TECHNOLOGY CONFERENCE (VTC2020-FALL)}, author={Cao, Liu and Yin, Hao and Hu, Jie and Zhang, Lyutianyang}, year={2020} }