Skip to main content

Liu Cui

West Chester University of PA, Computer Science, Faculty Member

Followers

11

Following

4

Co-authors

3

Public Views

My research interest broadly focuses on the comprehensive risk management and optimization of resource sharing systems. Several resource sharing systems exist; for example, smart grids, computer and vehicular networks, cloud, distributed sensor networks, and spectrum. Spectrum, which is the most valuable resource in the wireless communication field, forms the basis of my current research. I have examined the technology, policy, and economic aspects of spectrum access with one intention: to transform spectrum sharing from a radical strategy to commercial reality by understanding and minimizing risks for spectrum users and optimizing spectrum allocation.

As a PhD candidate, I am an energetic, open-minded, and optimistic team player. As an independent researcher, I am hard working and fast learning.

Specialties: Wireless Communications, Dynamic Spectrum Access, technical and policy issues of information networks.

Skills: Risk management and analysis, Optimization, Queueing models

Opportunities that I am looking for: Tenure-track positions in higher education and networks related research positions.
Supervisors: Martin Weiss

less

B. Harun Küçük

University of Pennsylvania

Ashok K Karmokar

University of British Columbia

Tallinn University of Technology

Kwantlen Polytechnic University

Kansas State University

University of Cologne

Armando Marques-Guedes

UNL - New University of Lisbon

Marianna Sigala

University of South Australia

University of Canberra

Andrew W Wilkins

Goldsmiths, University of London

Interests

Uploads

Papers by Liu Cui

Enforcement in Dynamic Spectrum Access Systems

by Mohammed Altamimi, Martin Weiss, Liu Cui, and William Lehr

The spectrum access rights granted by the Federal government to spectrum users come with the expe... more The spectrum access rights granted by the Federal government to spectrum users come with the expectation of protection from harmful interference. As a consequence of the growth of wireless demand and services of all types, technical progress enabling smart agile radio networks, and on-going spectrum management reform, there is both a need and opportunity to use and share spectrum more intensively and dynamically.

Tradeable Spectrum Interference Rights

by Martin Weiss and Liu Cui

Abstract: Spectrum rights have gained increasing attention since Ronald Coase pointed out that th... more Abstract: Spectrum rights have gained increasing attention since Ronald Coase pointed out that the most efficient way to assign spectrum is to give it to those users who value it most through property-like rights and secondary markets. Defining spectrum rights turns out to be difficult due to the nature of electronic emissions [1]. As a result, it may be more practical to define interference rights (similar to pollution rights) rather than exclusive usage rights.

Can unlicensed bands be used by unlicensed usage?

The Hinges of Destiny: A Decision Analysis of Spectrum Users’ Choices

Dynamic spectrum access (DSA) has been a technological approach that has received considerable re... more Dynamic spectrum access (DSA) has been a technological approach that has received considerable research attention over the past decade. At the same time, the relative paucity of deployed systems using some of these technologies speaks to either a mismatch between research priorities and practical needs, regulatory immaturity, technology immaturity, or a combination of these. In this paper, we examine the business decision that a spectrum entrant must take with regard to technology choice. We use a simple decision-analytic framework using standard Net Present Value (NPV) calculations to analyze that decision. Our conclusion is that, using the rough cost estimates and a simple system model, that exclusive use offers a higher NPV than the alternatives.

Decoupling Trust and Wireless Channel Induced Effects on Collaborative Sensing Attacks

One of the most crucial functionalities of cognitive radio networks is spectrum sensing. Completi... more One of the most crucial functionalities of cognitive radio networks is spectrum sensing. Completing this task in an accurate manner requires opportunistic spectrum access. Traditionally, sensing has been performed through energy detection by each individual secondary user. In order to increase accuracy, individual measurements are aggregated using different fusion functions. However, even though collaborative spectrum sensing can increase accuracy under benign settings, it is prone to falsification attacks, where malicious secondary users report fake sensings. Previous studies have designed trust (reputation) based systems to contain the effect of the adversaries, ignoring to a large extent the wireless channel irregularities when performing the computation. In this paper, we decouple the reasons behind a false sensing report and propose the Decoupling Trust and Capability Spectrum Sensing System (DTCS 3 ). DTCS 3 is a collaborative spectrum sensing system that takes into account both a secondary sensor node's trust and its capability to sense the channel. Through thorough evaluations that consider a large variety of attack strategies, we show that by accounting for wireless induced effects while calculating the reporting trust of a secondary user, we can significantly improve the performance of a collaborative spectrum sensing system as compared to existing schemes in the literature. In particular, the true positive/negative rates can be improved by as much as 36%, while DTCS 3 is able to track and respond to dynamic changes in the adversaries behavior.

Spectrum Trading with Interference Rights

Spectrum, which supports the transmission of sound, data, and video, is critical to the implement... more Spectrum, which supports the transmission of sound, data, and video, is critical to the implementation of mobile connected society. Federal Communications Commission (FCC) has been seeking policies that offer more spectrum access opportunities, such as secondary spectrum market and TV white space. In this paper, we develop the idea of trading spectrum in Interference Right. It means to alleviate the spectrum scarcity by cooperative spectrum usage and making the spectrum market as liquid as possible. We use some plausible case studies to illustrate the characteristics and features. The paper therefore includes a detailed description of trading procedures along with some first order quantitative modeling of the cases coupled with qualitative analysis.

Dynamic Geospatial Spectrum Modelling: Taxonomy, Options and Consequences

Much of the research in Dynamic Spectrum Access (DSA) has focused on opportunistic access in the ... more Much of the research in Dynamic Spectrum Access (DSA) has focused on opportunistic access in the temporal domain. While this has been quite useful in establishing the technical feasibility of DSA systems, it has missed large sections of the overall DSA problem space. In this paper, we argue that the spatiotemporal operating context of specific environments matters to the selection of the appropriate technology for learning context information. We identify twelve potential operating environments and compare four context awareness approaches (on-board sensing, databases, sensor networks, and cooperative sharing) for these environments. Since our point of view is overall system cost and efficiency, this analysis has utility for those regulators whose objectives are reducing system costs and enhancing system efficiency. We conclude that regulators should pay attention to the operating environment of DSA systems when determining which approaches to context learning to encourage.

Dimensions of cooperative spectrum sharing: Rights and enforcement

Sharing of radio spectrum requires a careful and nuanced understanding of the rights of incumbent... more Sharing of radio spectrum requires a careful and nuanced understanding of the rights of incumbents and spectrum entrants. In addition, the dynamics of stakeholders can be understood by examining how various rights are arranged (and rearranged) among them. Importantly, understanding the rights and their distribution is the predicate to developing rational and useful enforcement approaches.

Coopetive Spectrum Trading –Creating Endogenous Spectrum Holes

Dynamic spectrum access has been proposed to address the spectrum scarcity. Based on this access ... more Dynamic spectrum access has been proposed to address the spectrum scarcity. Based on this access mode, secondary users are allowed to opportunistically operate when primary users are absent. They are, however, required to relinquish the spectrum upon return of the incumbent spectrum holder. Although it improves spectrum utility, opportunistic spectrum access limits secondary users' access to exogenous spectrum holes vacated by primary users. We argue that spectrum holes should be endogenous, enabled by incentives to incumbent users to increase spectrum availability, while mitigating risk. To this end, we take a different perspective on dynamic spectrum sharing and propose a coopetive framework, whereby primary and secondary users engage in a cooperative, yet competitive, auction-driven spectrum sharing to enhance spectrum usage. Further, we trade spectrum financial options to increase the trading flexibility and capture the value primary and secondary users attach to spectrum access and usage. We show that spectrum trading, which combines revocable and exclusive leasing, provides higher utilities for both primary and secondary users.

Enforcement in Dynamic Spectrum Access Systems

by Mohammed Altamimi, Martin Weiss, Liu Cui, and William Lehr

The spectrum access rights granted by the Federal government to spectrum users come with the expe... more The spectrum access rights granted by the Federal government to spectrum users come with the expectation of protection from harmful interference. As a consequence of the growth of wireless demand and services of all types, technical progress enabling smart agile radio networks, and on-going spectrum management reform, there is both a need and opportunity to use and share spectrum more intensively and dynamically.

Tradeable Spectrum Interference Rights

by Martin Weiss and Liu Cui

Abstract: Spectrum rights have gained increasing attention since Ronald Coase pointed out that th... more Abstract: Spectrum rights have gained increasing attention since Ronald Coase pointed out that the most efficient way to assign spectrum is to give it to those users who value it most through property-like rights and secondary markets. Defining spectrum rights turns out to be difficult due to the nature of electronic emissions [1]. As a result, it may be more practical to define interference rights (similar to pollution rights) rather than exclusive usage rights.

Can unlicensed bands be used by unlicensed usage?

The Hinges of Destiny: A Decision Analysis of Spectrum Users’ Choices

Dynamic spectrum access (DSA) has been a technological approach that has received considerable re... more Dynamic spectrum access (DSA) has been a technological approach that has received considerable research attention over the past decade. At the same time, the relative paucity of deployed systems using some of these technologies speaks to either a mismatch between research priorities and practical needs, regulatory immaturity, technology immaturity, or a combination of these. In this paper, we examine the business decision that a spectrum entrant must take with regard to technology choice. We use a simple decision-analytic framework using standard Net Present Value (NPV) calculations to analyze that decision. Our conclusion is that, using the rough cost estimates and a simple system model, that exclusive use offers a higher NPV than the alternatives.

Decoupling Trust and Wireless Channel Induced Effects on Collaborative Sensing Attacks

One of the most crucial functionalities of cognitive radio networks is spectrum sensing. Completi... more One of the most crucial functionalities of cognitive radio networks is spectrum sensing. Completing this task in an accurate manner requires opportunistic spectrum access. Traditionally, sensing has been performed through energy detection by each individual secondary user. In order to increase accuracy, individual measurements are aggregated using different fusion functions. However, even though collaborative spectrum sensing can increase accuracy under benign settings, it is prone to falsification attacks, where malicious secondary users report fake sensings. Previous studies have designed trust (reputation) based systems to contain the effect of the adversaries, ignoring to a large extent the wireless channel irregularities when performing the computation. In this paper, we decouple the reasons behind a false sensing report and propose the Decoupling Trust and Capability Spectrum Sensing System (DTCS 3 ). DTCS 3 is a collaborative spectrum sensing system that takes into account both a secondary sensor node's trust and its capability to sense the channel. Through thorough evaluations that consider a large variety of attack strategies, we show that by accounting for wireless induced effects while calculating the reporting trust of a secondary user, we can significantly improve the performance of a collaborative spectrum sensing system as compared to existing schemes in the literature. In particular, the true positive/negative rates can be improved by as much as 36%, while DTCS 3 is able to track and respond to dynamic changes in the adversaries behavior.

Spectrum Trading with Interference Rights

Spectrum, which supports the transmission of sound, data, and video, is critical to the implement... more Spectrum, which supports the transmission of sound, data, and video, is critical to the implementation of mobile connected society. Federal Communications Commission (FCC) has been seeking policies that offer more spectrum access opportunities, such as secondary spectrum market and TV white space. In this paper, we develop the idea of trading spectrum in Interference Right. It means to alleviate the spectrum scarcity by cooperative spectrum usage and making the spectrum market as liquid as possible. We use some plausible case studies to illustrate the characteristics and features. The paper therefore includes a detailed description of trading procedures along with some first order quantitative modeling of the cases coupled with qualitative analysis.

Dynamic Geospatial Spectrum Modelling: Taxonomy, Options and Consequences

Much of the research in Dynamic Spectrum Access (DSA) has focused on opportunistic access in the ... more Much of the research in Dynamic Spectrum Access (DSA) has focused on opportunistic access in the temporal domain. While this has been quite useful in establishing the technical feasibility of DSA systems, it has missed large sections of the overall DSA problem space. In this paper, we argue that the spatiotemporal operating context of specific environments matters to the selection of the appropriate technology for learning context information. We identify twelve potential operating environments and compare four context awareness approaches (on-board sensing, databases, sensor networks, and cooperative sharing) for these environments. Since our point of view is overall system cost and efficiency, this analysis has utility for those regulators whose objectives are reducing system costs and enhancing system efficiency. We conclude that regulators should pay attention to the operating environment of DSA systems when determining which approaches to context learning to encourage.

Dimensions of cooperative spectrum sharing: Rights and enforcement

Sharing of radio spectrum requires a careful and nuanced understanding of the rights of incumbent... more Sharing of radio spectrum requires a careful and nuanced understanding of the rights of incumbents and spectrum entrants. In addition, the dynamics of stakeholders can be understood by examining how various rights are arranged (and rearranged) among them. Importantly, understanding the rights and their distribution is the predicate to developing rational and useful enforcement approaches.

Coopetive Spectrum Trading –Creating Endogenous Spectrum Holes

Dynamic spectrum access has been proposed to address the spectrum scarcity. Based on this access ... more Dynamic spectrum access has been proposed to address the spectrum scarcity. Based on this access mode, secondary users are allowed to opportunistically operate when primary users are absent. They are, however, required to relinquish the spectrum upon return of the incumbent spectrum holder. Although it improves spectrum utility, opportunistic spectrum access limits secondary users' access to exogenous spectrum holes vacated by primary users. We argue that spectrum holes should be endogenous, enabled by incentives to incumbent users to increase spectrum availability, while mitigating risk. To this end, we take a different perspective on dynamic spectrum sharing and propose a coopetive framework, whereby primary and secondary users engage in a cooperative, yet competitive, auction-driven spectrum sharing to enhance spectrum usage. Further, we trade spectrum financial options to increase the trading flexibility and capture the value primary and secondary users attach to spectrum access and usage. We show that spectrum trading, which combines revocable and exclusive leasing, provides higher utilities for both primary and secondary users.