Ciyuan Zhang | Columbia University (original) (raw)

Books by Ciyuan Zhang

Research paper thumbnail of Communication Networks An Optimization Control and Stochastic Networks Perspective

Communication Networks blends control, optimization, and stochastic network theories with feature... more Communication Networks blends control, optimization, and stochastic network theories with features that support student learning to provide graduate students with an accessible, modern approach to the design of communication networks.

Papers by Ciyuan Zhang

Research paper thumbnail of Coded Caching with Heterogeneous User Profiles

arXiv (Cornell University), Jan 25, 2022

Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order... more Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order to balance the traffic load in communication networks. Several works have studied the achievable peak and average rates under different conditions: variable file lengths or popularities, variable cache sizes, decentralized networks, etc. However, very few have considered the possibility of heterogeneous user profiles, despite modern content providers are investing heavily in categorizing users according to their habits and preferences. This paper proposes three coded caching schemes with uncoded pre-fetching for scenarios where end users are grouped into classes with different file demand sets (FDS). One scheme ignores the difference between the classes, another ignores the intersection between them and the third decouples the delivery of files common to all FDS from those unique to a single class. The transmission rates of the three schemes are compared with a lower bound to evaluate their gap to optimality, and with each other to show that each scheme can outperform the other two when certain conditions are met.

Research paper thumbnail of Networked Competitive Multi-Virus SIR Model

Networked Competitive Multi-Virus SIR Model

2022 American Control Conference (ACC)

Research paper thumbnail of A Networked Competitive Multi-Virus SIR Model: Analysis and Observability

IFAC-PapersOnLine

This paper proposes a novel discrete-time multi-virus SIR (susceptible-infectedrecovered) model t... more This paper proposes a novel discrete-time multi-virus SIR (susceptible-infectedrecovered) model that captures the spread of competing SIR epidemics over a population network. First, we provide a sufficient condition for the infection level of all the viruses over the networked model to converge to zero in exponential time. Second, we propose an observation model which captures the summation of all the viruses' infection levels in each node, which represents the individuals who are infected by different viruses but share similar symptoms. We present a sufficient condition for the model to be locally observable. We propose a Luenberger observer for the system state estimation and show via simulations that the estimation error of the Luenberger observer converges to zero before the viruses die out.

Research paper thumbnail of Coded Caching with Heterogeneous User Profiles

IEEE Transactions on Information Theory

Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order... more Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order to balance the traffic load in communication networks. Several works have studied the achievable peak and average rates under different conditions: variable file lengths or popularities, variable cache sizes, decentralized networks, etc. However, very few have considered the possibility of heterogeneous user profiles, despite modern content providers are investing heavily in categorizing users according to their habits and preferences. This paper proposes three coded caching schemes with uncoded pre-fetching for scenarios where end users are grouped into classes with different file demand sets (FDS). One scheme ignores the difference between the classes, another ignores the intersection between them and the third decouples the delivery of files common to all FDS from those unique to a single class. The transmission rates of the three schemes are compared with a lower bound to evaluate their gap to optimality, and with each other to show that each scheme can outperform the other two when certain conditions are met.

Research paper thumbnail of A Flexible Phased-Array Architecture for Reception and Rapid Direction-of-Arrival Finding Utilizing Pseudo-Random Antenna Weight Modulation and Compressive Sampling

IEEE Journal of Solid-State Circuits, 2019

The direct space-to-information converter (DSIC) unifies conventional delay-and-sum analog conven... more The direct space-to-information converter (DSIC) unifies conventional delay-and-sum analog conventional beamforming (CBF) with compressive sampling (CS) rapid direction-of-arrival (DOA) finding into a single, reconfigurable phased-array receiver architecture. Where current CBF-based DOA scanners need to exhaustively search through multiple DOA angles, the DSIC is able to receive energy from all possible angles by modulating its antenna weights psuedo-randomly. The DSIC RF-ASIC can operate from 1 to 3 GHz, was fabricated in 65-nm CMOS, and includes eight direct-conversion paths each delivering 32-dB conversion gain, 3.3-dBm in-band IIP3, and 6.4-dB NF while consuming 19.8 mW from 1.2 V. The DSIC RF-ASIC has two modes of operation, CS-DOA and CBF-Reception and can switch between them in less than 1 µs. In CS-DOA mode, the DSIC RF-ASIC finds the DOA of a single signal in 1 µs consuming 158 nJ which is 4× faster and 1.5× less energy than a comparable CBF-based DOA scanner.

Research paper thumbnail of An 8-Element, 1-3GHz Direct Space-to-Information Converter for Rapid, Compressive-Sampling Direction-of-Arrival Finding Utilizing Pseudo-Random Antenna-Weight Modulation

2018 IEEE Radio Frequency Integrated Circuits Symposium (RFIC)

Research paper thumbnail of On the Average Rate for Coded Caching with Heterogeneous User Profiles

ICC 2020 - 2020 IEEE International Conference on Communications (ICC)

Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order... more Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order to balance the traffic load in communication networks. Most of the existing research focuses on reducing the peak transmission rates with homogeneous file popularities, despite modern systems are often able to categorize users by their preferences and tend to care more about the average rather than peak rate. This paper considers a scenario with heterogeneous user profiles and analyzes the average transmission rates for three coded caching schemes under the assumption that each user can only request a subset of the total available files. In addition, it evaluates the average rate of the three schemes when the number of files is much larger than the number of users and the amount of cache memory. Furthermore, it proposes methods of cache allocations which minimize the average rate when the users have relatively small storage. Our results demonstrate connections between cache distributions which result in minimal average rate and peak rate. t distinct segments, where

Research paper thumbnail of The Effect of Population Flow on Epidemic Spread: Analysis and Control

In this paper, we present a discrete-time networked SEIR model using population flow, its derivat... more In this paper, we present a discrete-time networked SEIR model using population flow, its derivation, and assumptions under which this model is well defined. We identify properties of the system’s equilibria, namely the healthy states. We show that the set of healthy states is asymptotically stable, and that the value of the equilibria becomes equal across all sub-populations as a result of the network flow model. Furthermore, we explore closed-loop feedback control of the system by limiting flow between sub-populations as a function of the current infected states. These results are illustrated via simulation based on flight traffic between major airports in the United States. We find that a flow restriction strategy combined with a vaccine roll-out significantly reduces the total number of infections over the course of an epidemic, given that the initial flow restriction response is not delayed.

Research paper thumbnail of Estimation and Distributed Eradication of SIR Epidemics on Networks

This work examines the discrete-time networked SIR (susceptible-infected-recovered) epidemic mode... more This work examines the discrete-time networked SIR (susceptible-infected-recovered) epidemic model, where the infection and recovery parameters may be time-varying. We provide a sufficient condition for the SIR model to converge to the set of healthy states exponentially. We propose a stochastic framework to estimate the system states from observed testing data and provide an analytic expression for the error of the estimation algorithm. Employing the estimated and the true system states, we provide two novel eradication strategies that guarantee at least exponential convergence to the set of healthy states. We illustrate the results via simulations over northern Indiana, USA.

Research paper thumbnail of Communication Networks An Optimization Control and Stochastic Networks Perspective

Communication Networks blends control, optimization, and stochastic network theories with feature... more Communication Networks blends control, optimization, and stochastic network theories with features that support student learning to provide graduate students with an accessible, modern approach to the design of communication networks.

Research paper thumbnail of Coded Caching with Heterogeneous User Profiles

arXiv (Cornell University), Jan 25, 2022

Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order... more Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order to balance the traffic load in communication networks. Several works have studied the achievable peak and average rates under different conditions: variable file lengths or popularities, variable cache sizes, decentralized networks, etc. However, very few have considered the possibility of heterogeneous user profiles, despite modern content providers are investing heavily in categorizing users according to their habits and preferences. This paper proposes three coded caching schemes with uncoded pre-fetching for scenarios where end users are grouped into classes with different file demand sets (FDS). One scheme ignores the difference between the classes, another ignores the intersection between them and the third decouples the delivery of files common to all FDS from those unique to a single class. The transmission rates of the three schemes are compared with a lower bound to evaluate their gap to optimality, and with each other to show that each scheme can outperform the other two when certain conditions are met.

Research paper thumbnail of Networked Competitive Multi-Virus SIR Model

Networked Competitive Multi-Virus SIR Model

2022 American Control Conference (ACC)

Research paper thumbnail of A Networked Competitive Multi-Virus SIR Model: Analysis and Observability

IFAC-PapersOnLine

This paper proposes a novel discrete-time multi-virus SIR (susceptible-infectedrecovered) model t... more This paper proposes a novel discrete-time multi-virus SIR (susceptible-infectedrecovered) model that captures the spread of competing SIR epidemics over a population network. First, we provide a sufficient condition for the infection level of all the viruses over the networked model to converge to zero in exponential time. Second, we propose an observation model which captures the summation of all the viruses' infection levels in each node, which represents the individuals who are infected by different viruses but share similar symptoms. We present a sufficient condition for the model to be locally observable. We propose a Luenberger observer for the system state estimation and show via simulations that the estimation error of the Luenberger observer converges to zero before the viruses die out.

Research paper thumbnail of Coded Caching with Heterogeneous User Profiles

IEEE Transactions on Information Theory

Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order... more Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order to balance the traffic load in communication networks. Several works have studied the achievable peak and average rates under different conditions: variable file lengths or popularities, variable cache sizes, decentralized networks, etc. However, very few have considered the possibility of heterogeneous user profiles, despite modern content providers are investing heavily in categorizing users according to their habits and preferences. This paper proposes three coded caching schemes with uncoded pre-fetching for scenarios where end users are grouped into classes with different file demand sets (FDS). One scheme ignores the difference between the classes, another ignores the intersection between them and the third decouples the delivery of files common to all FDS from those unique to a single class. The transmission rates of the three schemes are compared with a lower bound to evaluate their gap to optimality, and with each other to show that each scheme can outperform the other two when certain conditions are met.

Research paper thumbnail of A Flexible Phased-Array Architecture for Reception and Rapid Direction-of-Arrival Finding Utilizing Pseudo-Random Antenna Weight Modulation and Compressive Sampling

IEEE Journal of Solid-State Circuits, 2019

The direct space-to-information converter (DSIC) unifies conventional delay-and-sum analog conven... more The direct space-to-information converter (DSIC) unifies conventional delay-and-sum analog conventional beamforming (CBF) with compressive sampling (CS) rapid direction-of-arrival (DOA) finding into a single, reconfigurable phased-array receiver architecture. Where current CBF-based DOA scanners need to exhaustively search through multiple DOA angles, the DSIC is able to receive energy from all possible angles by modulating its antenna weights psuedo-randomly. The DSIC RF-ASIC can operate from 1 to 3 GHz, was fabricated in 65-nm CMOS, and includes eight direct-conversion paths each delivering 32-dB conversion gain, 3.3-dBm in-band IIP3, and 6.4-dB NF while consuming 19.8 mW from 1.2 V. The DSIC RF-ASIC has two modes of operation, CS-DOA and CBF-Reception and can switch between them in less than 1 µs. In CS-DOA mode, the DSIC RF-ASIC finds the DOA of a single signal in 1 µs consuming 158 nJ which is 4× faster and 1.5× less energy than a comparable CBF-based DOA scanner.

Research paper thumbnail of An 8-Element, 1-3GHz Direct Space-to-Information Converter for Rapid, Compressive-Sampling Direction-of-Arrival Finding Utilizing Pseudo-Random Antenna-Weight Modulation

2018 IEEE Radio Frequency Integrated Circuits Symposium (RFIC)

Research paper thumbnail of On the Average Rate for Coded Caching with Heterogeneous User Profiles

ICC 2020 - 2020 IEEE International Conference on Communications (ICC)

Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order... more Coded caching utilizes pre-fetching during off-peak hours and multi-casting for delivery in order to balance the traffic load in communication networks. Most of the existing research focuses on reducing the peak transmission rates with homogeneous file popularities, despite modern systems are often able to categorize users by their preferences and tend to care more about the average rather than peak rate. This paper considers a scenario with heterogeneous user profiles and analyzes the average transmission rates for three coded caching schemes under the assumption that each user can only request a subset of the total available files. In addition, it evaluates the average rate of the three schemes when the number of files is much larger than the number of users and the amount of cache memory. Furthermore, it proposes methods of cache allocations which minimize the average rate when the users have relatively small storage. Our results demonstrate connections between cache distributions which result in minimal average rate and peak rate. t distinct segments, where

Research paper thumbnail of The Effect of Population Flow on Epidemic Spread: Analysis and Control

In this paper, we present a discrete-time networked SEIR model using population flow, its derivat... more In this paper, we present a discrete-time networked SEIR model using population flow, its derivation, and assumptions under which this model is well defined. We identify properties of the system’s equilibria, namely the healthy states. We show that the set of healthy states is asymptotically stable, and that the value of the equilibria becomes equal across all sub-populations as a result of the network flow model. Furthermore, we explore closed-loop feedback control of the system by limiting flow between sub-populations as a function of the current infected states. These results are illustrated via simulation based on flight traffic between major airports in the United States. We find that a flow restriction strategy combined with a vaccine roll-out significantly reduces the total number of infections over the course of an epidemic, given that the initial flow restriction response is not delayed.

Research paper thumbnail of Estimation and Distributed Eradication of SIR Epidemics on Networks

This work examines the discrete-time networked SIR (susceptible-infected-recovered) epidemic mode... more This work examines the discrete-time networked SIR (susceptible-infected-recovered) epidemic model, where the infection and recovery parameters may be time-varying. We provide a sufficient condition for the SIR model to converge to the set of healthy states exponentially. We propose a stochastic framework to estimate the system states from observed testing data and provide an analytic expression for the error of the estimation algorithm. Employing the estimated and the true system states, we provide two novel eradication strategies that guarantee at least exponential convergence to the set of healthy states. We illustrate the results via simulations over northern Indiana, USA.