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Chau Yuen

Singapore University of Technology and Design (SUTD), Engineering Product Development, Faculty Member

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Indonesian Journal of Electrical Engineering and Computer Science

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Korea Advanced Institute of Science and Technology

King Saud University

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Papers by Chau Yuen

A coalition formation game framework for peer-to-peer energy trading

Applied Energy, 2020

This paper studies social cooperation backed peer-to-peer energy trading technique by which prosu... more This paper studies social cooperation backed peer-to-peer energy trading technique by which prosumers can decide how they can use their batteries opportunistically for participating in the peer-to-peer trading. The objective is to achieve a solution in which the ultimate beneficiaries are the prosumers, i.e., a prosumer-centric solution. To do so, a coalition formation game is designed, which enables a prosumer to compare its benefit of participating in the peer-to-peer trading with and without using its battery and thus, allows the prosumer to form suitable social coalition groups with other similar prosumers in the network for conducting peer-to-peer trading. The properties of the formed coalitions are studied, and it is shown that 1) the coalition structure that stems from the social cooperation between participating prosumers at each time slot is both stable and optimal, and 2) the outcomes of the proposed peerto-peer trading scheme is prosumer-centric. Case studies are conducted based on real household energy usage and solar generation data to highlight how the proposed scheme can benefit prosumers through exhibiting prosumer-centric properties.

Cost-aware demand scheduling for delay tolerant applications

Journal of Network and Computer Applications, 2015

In this paper, we study the problem of demand scheduling for delay tolerant applications. With re... more In this paper, we study the problem of demand scheduling for delay tolerant applications. With regard to the time-varying resource cost per unit size of the demand, we study two optimization problems: (1) how to minimize the peak resource usage, while making sure that each demand is served before the deadline; (2) how to minimize the longest completion time of all the demands under a given maximum allowable resource constraint. For the first problem, we prove that it is NP-hard, under the general setting that the demands are of different sizes and require several continuous time slots to complete. We then provide an integer linear programming solution, and propose an efficient heuristic algorithm. For a special case of the same size demand and single serving time slot, the proposed algorithm is proved to be optimal. We further study a special case that all the demands have the same deadline, and prove that the proposed algorithm can achieve three times the optimal solution if the number of serving time slots required for each demand is at most two. For the second problem, we also prove it to be NP-hard and formulate it into an integer linear programming. An efficient polynomial-time algorithm is then proposed, whose completion time is proved to be at most two times the optimal minimum completion time under a specific setting. Finally, simulation results demonstrate the superiorities of the proposed schemes.

Smart-grid communications and standards

Communication, Control and Security for the Smart Grid

A reliable and efficient communication and networking infrastructure will connect the functional ... more A reliable and efficient communication and networking infrastructure will connect the functional elements within the smart grid. Different physical data communication technologies for the smart grid will empower the legacy power grid with the capability to support two-way energy and information flow. The smart grid will rely on several existing and future wired and wireless communication technologies (e.g., power line communication, cellular network, internet protocol networks, ZigBee, Wi-Fi, Worldwide Interoperability for Microwave Access, etc.). Also, advanced techniques for accessing the network and routing the information to the different nodes of the network will be required. In this chapter, we discuss smart-grid communication network and divide it into three tiers, i.e., home area network, neighborhood area network, and wide-area network. We present smart-grid communication technologies, standards, and protocols for the physical layer operations. We next discuss the medium access control (MAC) and network layer protocols of the smart-grid communication technologies. In the end, we present a case study for the implementation and performance evaluation of various smart-grid algorithms and communication infrastructure.

A quasi-orthogonal STBC design for SC-FDMA in LTE-advanced

21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2010

ABSTRACT In this paper, a class of quasi-orthogonal space-time block codes (Q-STBC) is proposed f... more ABSTRACT In this paper, a class of quasi-orthogonal space-time block codes (Q-STBC) is proposed for systems with 2 antennas and 3 time slots, where the orthogonal Alamouti code can not be applied due to the “odd symbol” problem inherited in the 3GPP frame structure. The proposed codes can achieve rate one and full diversity with lower complexity maximum likelihood detection. The design takes into consideration the signal power fluctuation and minimizes the potential peak-to-average ratio (PAPR) in the transmitted signals. The application to Single Carrier Frequency Division Multiple Access (SC-FDMA) has been investigated further. A transmission scheme is proposed to preserve the good PAPR property of SC-FDMA. In addition, linear and iterative decoding algorithms are proposed to simplify the receiver complexity. Simulations have been conducted to demonstrate the superior performance.

Location-Aware Spectrum and Power Allocation in Joint Cognitive Communication-Radar Networks

Proceedings of the 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2011

A novel approach to spectrum and power allocation is proposed for joint cognitive communication-r... more A novel approach to spectrum and power allocation is proposed for joint cognitive communication-radar networks, which aim at integrating cognitive radio (CR-o) and cognitive radar (CR-r) paradigms to achieve intelligent utilization of spectrum resources in wireless networks. This approach exploits the location information offered by CR-r combined with spectrum sensing capability of CR-o to aid spectrum and power allocation by minimizing harmful interference among neighboring devices. Such systems require both coexistence and sharing of perception of radio environment and radar scene. To offer better spectrum resource utilization, entropy of the received signal is employed in order to detect spectrum holes over the network topology. This entropy-based technique also demonstrates superior performance as compared to the conventional method based on energy detection. Simulation results indicate both throughput improvement and interference reduction among neighboring devices.

Peak-to-Average Ratio Constrained Demand-Side Management With Consumer's Preference in Residential Smart Grid

IEEE Journal of Selected Topics in Signal Processing, 2014

In a smart grid network, demand-side management plays a significant role in allowing consumers, i... more In a smart grid network, demand-side management plays a significant role in allowing consumers, incentivized by utilities, to manage their energy consumption. This can be done through shifting consumption to off-peak hours and thus reducing the peak-to-average ratio (PAR) of the electricity system. In this paper, we begin by proposing a demand-side energy consumption scheduling scheme for household appliances that considers a PAR constraint. An initial optimization problem is formulated to minimize the energy cost of the consumers through the determination of the optimal usage power and operation time of throttleable and shiftable appliances, respectively. We realize that the acceptance of consumers of these load management schemes is crucial to its success. Hence, we then introduce a multi-objective optimization problem which not only minimizes the energy cost but also minimizes the inconvenience posed to consumers. In addition to solving the proposed optimization problems in a centralized manner, two distributed algorithms for the initial and the multi-objective optimization problems are also proposed. Simulation results show that the proposed demand-side energy consumption schedule can provide an effective approach to reducing total energy costs while simultaneously considering PAR constraints and consumers' preferences.

Feasibility of using discriminate pricing schemes for energy trading in smart grid

2014 IEEE Global Communications Conference, 2014

This paper investigates the feasibility of using a discriminate pricing scheme to offset the inco... more This paper investigates the feasibility of using a discriminate pricing scheme to offset the inconvenience that is experienced by an energy user (EU) in trading its energy with an energy controller in smart grid. The main objective is to encourage EUs with small distributed energy resources (DERs), or with high sensitivity to their inconvenience, to take part in the energy trading via providing incentive to them with relatively higher payment at the same time as reducing the total cost to the energy controller. The proposed scheme is modeled through a two-stage Stackelberg game that describes the energy trading between a shared facility authority (SFA) and EUs in a smart community. A suitable cost function is proposed for the SFA to leverage the generation of discriminate pricing according to the inconvenience experienced by each EU. It is shown that the game has a unique sub-game perfect equilibrium (SPE), under the certain condition at which the SFA's total cost is minimized, and that each EU receives its best utility according to its associated inconvenience for the given price. A backward induction technique is used to derive a closed form expression for the price function at SPE, and thus the dependency of price on an EU's different decision parameters is explained for the studied system. Numerical examples are provided to show the beneficial properties of the proposed scheme. Index Terms-Smart grid, discriminate pricing, distributed energy resources, game theory, energy management.

Trading Delay for Distortion in One-Way Video Communication Over the Internet

IEEE Transactions on Circuits and Systems for Video Technology, 2016

We study the problem of one-way video communication in a single-source, multiple-destination scen... more We study the problem of one-way video communication in a single-source, multiple-destination scenario over the lossy Internet. Forward error correction (FEC) coding is commonly adopted for data protection in implementing loss-resilient video transmission systems. However, the burst packet losses over the Internet frequently degrade FEC performance and induce video quality deteriorations. To address the challenging problem, we propose a novel transmission scheme dubbed trading delay for distortion (TELFORD) that includes three components: 1) adaptive multidestination status estimation; 2) delay-constrained transmission rate assignment; and 3) differentiated FEC packet spreading. We analytically formulate and solve the problem of FEC packet allocation and scheduling to minimize the end-to-end video distortion. The proposed TELFORD is able to cope with multiple-destination scheduling separately. We conduct performance evaluation through semiphysical emulations in Exata using real-time H.264 video streaming. Experimental results show that TELFORD outperforms existing error control transmission schemes in improving the video peak signal-to-noise ratio and mitigating packet transmission impairments.

New High-Rate STBC With Good Dispersion Property

2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications

... NEW HIGH-RATE STBC WITH GOOD DISPERSION PROPERTY Yong Liang Guan Tjeng Thiang Tjhung Nanyang ... more

Energy Efficient Multicast Routing in Mobile Ad Hoc Networks

Lecture Notes in Computer Science, 2003

In this paper, we address the problem of multicast routing in mobile ad-hoc networks from the vie... more In this paper, we address the problem of multicast routing in mobile ad-hoc networks from the viewpoint of energy efficiency. In an ad-hoc wireless network, each node runs on a local energy source which has a limited energy life span. Thus, energy conservation is a critical issue in mobile ad-hoc networks. One approach for energy conservation is to establish routes that require lowest total energy consumption. This optimization problem is referred as the minimum-energy multicast routing problem (MEMRP). In this paper, propose new efficient heuristic algorithms for the construction of energyefficient multicast routes in mobile ad-hoc networks. These algorithms exploit the broadcast nature of the wireless channel, and address the need for energyefficient operations. Empirical studies show that our algorithms are able to achieve better performance than algorithms that have been developed for MEMRP.

Bi-Directional Multi-Antenna Relay Communications with Wireless Network Coding

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

In this paper, we consider a two-way or bidirectional communications system with a relay equipped... more In this paper, we consider a two-way or bidirectional communications system with a relay equipped with multiple antennas. We show that when the downlink channel state information is not known at the relay, the benefit of having additional antennas at the relay can only be obtained by using decode and forward (DF) but not amplify and forward (AF). The gain becomes significant when we employ transmit diversity together with wireless network coding. We also demonstrate how the performance of such system can be improved by performing antenna selection at the relay. Our results show that if downlink channel state information is known at the relay, network coding may not provide additional gain than simple antenna selection scheme.

Decentralized block diagonalization algorithms for distributed MIMO systems

International Symposium on Wireless and Pervasive Computing, 2011

Page 1. Decentralized Block Diagonalization Algorithms for Distributed MIMO Systems Mauricio Mora... more

Optimizing quasi-orthogonal STBC through group-constrained linear transformation

IEEE Global Telecommunications Conference, 2004. GLOBECOM '04.

In this paper, we first derive the generic algebraic structure of a Quasi-Orthogonal STBC (QO-STB... more In this paper, we first derive the generic algebraic structure of a Quasi-Orthogonal STBC (QO-STBC). Next we propose Group-Constrained Linear Transformation (GCLT) as a means to optimize the diversity and coding gains of a QO-STBC with square or rectangular QAM constellations. Compared with QO-STBC with constellation rotation (CR), we show that QO-STBC with GCLT requires only half the number of symbols for joint detection, hence lower maximum-likelihood decoding complexity. We also derive analytically the optimum GCLT parameters for QO-STBC with square QAM constellation. The optimized QO-STBCs with GCLT are able to achieve full transmit diversity, and have negligible performance loss compared with QO-STBCs with CR at the same code rate.

Construction of quasi orthogonal STBC with minimum decoding complexity

International Symposium onInformation Theory, 2004. ISIT 2004. Proceedings.

In this paper, we formulate the algebraic structure of Quasi-Orthogonal STBC with minimum decodin... more In this paper, we formulate the algebraic structure of Quasi-Orthogonal STBC with minimum decoding complexity (MDC-QOSTBC), whose maximum likelihood (ML) decoder only requires the joint detection of two real symbols, for any numbers of transmit antennas. We also propose a systematic method to construct an MDC-QOSTBC from an Orthogonal-STBC (O-STBC). The maximum code rate of the resultant MDC-QOSTBC is shown to be the same as that of the lower-order O-STBC used to construct it. We also find the optimum constellation rotation angle for the proposed MDC-QOSTBC construction to achieve full diversity and optimum coding gain. We can show that the proposed MDC-QOSTBC has more even power distribution over the transmit antennas, better scalability in adjusting the number of transmit antennas, and more superior decoding performance than the Coordinate Interleaved Orthogonal Design (CIOD) and Asymmetric CIOD.

Limited feedback for multi-antenna multi-user communications with Generalized Multi-Unitary Decomposition

2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, 2008

In this paper, we propose a decomposition method called Generalized Multi-Unitary Decomposition (... more

Channel Allocation in a Multiple Distributed Vehicular Users Using Game Theory

2010 IEEE 71st Vehicular Technology Conference, 2010

In this paper, we look into the channel allocation problem for a non-cooperative cognitive vehicu... more In this paper, we look into the channel allocation problem for a non-cooperative cognitive vehicular ad-hoc communication network with multiple communicating pairs distributed spatially apart. An algorithm which can search for all pure Nash Equilibrium (NE) solutions is presented. We study how the number of pure NEs grows when either the size of the network or the number of available channels gets higher. Myopic play of a game, in which the players take turn to choose its best response strategy, is a common approach to obtain one of these NE solutions, if the algorithm converges. However, we found that for myopic play of the game, the probability of convergence to the NE which has the desired best global utility is not guaranteed. We further propose two player ordering schemes to study how the probability of hitting the best global solution among all possible NEs is affected. We find that by allowing the node with the lowest "expected" utility to decide first increases the chance of hitting the NE solution with better utility value.

Unbalanced and Balanced 2-Group Decodable Spatial Multiplexing Code

2009 IEEE 70th Vehicular Technology Conference Fall, 2009

Spatial multiplexing code (SMC) has high transmission code rate but also high maximum likelihood ... more Spatial multiplexing code (SMC) has high transmission code rate but also high maximum likelihood (ML) decoding complexity. To overcome this disadvantage, we propose 2-group decodable SMC with full symbol-wise diversity for arbitrary number of transmit antennas. In this paper, unbalanced 2group decodable SMC is first constructed and used to construct balanced 2-group decodable SMC. The rates of both the unbalanced/balanced 2-group decodable SMCs approach Nt asymptotically when T Nt where Nt is the number of transmit antennas and T is the code length. To our best knowledge, this is the first time that 2-group decodable SMCs are constructed systematically.

Four-Node Relay Network with Bi-Directional Traffic Employing Wireless Network Coding with Pre-Cancellation

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

Network coding has the potential to improve the overall throughput of a network by combining diff... more Network coding has the potential to improve the overall throughput of a network by combining different streams of data and forwarding them. In wireless networks, the wireless channel provide an excellent medium for physical layer network coding as signals from different transmitters are combined automatically by the wireless channel. In such scenarios, it would be interesting to investigate protocols and algorithms which can optimally relay information. In this paper, we look at a four-node two-way or bidirectional relay network, and propose a relay protocol which can relay information efficiently in this network.

Beamforming matrix quantization with variable feedback rate

2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, 2008

We propose an improved beamforming matrix compression by Givens Rotation with the use of variable... more We propose an improved beamforming matrix compression by Givens Rotation with the use of variable feedback rate. The variable feedback rate means that the number of bits used to represent the quantized beamforming matrix is based on the value of the matrix. Compared with the fixed feedback rate scheme, the proposed method has better performance without additional feedback bandwidth.

Non-homogeneous distributed storage systems

2012 50th Annual Allerton Conference on Communication, Control, and Computing (Allerton), 2012

This paper describes a non-homogeneous distributed storage systems (DSS), where there is one supe... more This paper describes a non-homogeneous distributed storage systems (DSS), where there is one super node which has a larger storage size and higher reliability and availability than the other storage nodes. We propose three distributed storage schemes based on (k + 2, k) maximum distance separable (MDS) codes and non-MDS codes to show the efficiency of such non-homogeneous DSS in terms of repair efficiency and data availability. Our schemes achieve optimal bandwidth k+1 2 M k when repairing 1-node failure, but require only one fourth of the minimum required file size and can operate with a smaller field size leading to significant complexity reduction than traditional homogeneous DSS. Moreover, with non-MDS codes, our scheme can achieve an even smaller repair bandwidth of M 2k. Finally, we show that our schemes can increase the data availability by 10% than the traditional homogeneous DSS scheme. Index Terms-Exact-repair MDS codes, non-homogeneous DSS, minimum storage regenerating (MSR) codes.

A coalition formation game framework for peer-to-peer energy trading

Applied Energy, 2020

This paper studies social cooperation backed peer-to-peer energy trading technique by which prosu... more This paper studies social cooperation backed peer-to-peer energy trading technique by which prosumers can decide how they can use their batteries opportunistically for participating in the peer-to-peer trading. The objective is to achieve a solution in which the ultimate beneficiaries are the prosumers, i.e., a prosumer-centric solution. To do so, a coalition formation game is designed, which enables a prosumer to compare its benefit of participating in the peer-to-peer trading with and without using its battery and thus, allows the prosumer to form suitable social coalition groups with other similar prosumers in the network for conducting peer-to-peer trading. The properties of the formed coalitions are studied, and it is shown that 1) the coalition structure that stems from the social cooperation between participating prosumers at each time slot is both stable and optimal, and 2) the outcomes of the proposed peerto-peer trading scheme is prosumer-centric. Case studies are conducted based on real household energy usage and solar generation data to highlight how the proposed scheme can benefit prosumers through exhibiting prosumer-centric properties.

Cost-aware demand scheduling for delay tolerant applications

Journal of Network and Computer Applications, 2015

In this paper, we study the problem of demand scheduling for delay tolerant applications. With re... more In this paper, we study the problem of demand scheduling for delay tolerant applications. With regard to the time-varying resource cost per unit size of the demand, we study two optimization problems: (1) how to minimize the peak resource usage, while making sure that each demand is served before the deadline; (2) how to minimize the longest completion time of all the demands under a given maximum allowable resource constraint. For the first problem, we prove that it is NP-hard, under the general setting that the demands are of different sizes and require several continuous time slots to complete. We then provide an integer linear programming solution, and propose an efficient heuristic algorithm. For a special case of the same size demand and single serving time slot, the proposed algorithm is proved to be optimal. We further study a special case that all the demands have the same deadline, and prove that the proposed algorithm can achieve three times the optimal solution if the number of serving time slots required for each demand is at most two. For the second problem, we also prove it to be NP-hard and formulate it into an integer linear programming. An efficient polynomial-time algorithm is then proposed, whose completion time is proved to be at most two times the optimal minimum completion time under a specific setting. Finally, simulation results demonstrate the superiorities of the proposed schemes.

Smart-grid communications and standards

Communication, Control and Security for the Smart Grid

A reliable and efficient communication and networking infrastructure will connect the functional ... more A reliable and efficient communication and networking infrastructure will connect the functional elements within the smart grid. Different physical data communication technologies for the smart grid will empower the legacy power grid with the capability to support two-way energy and information flow. The smart grid will rely on several existing and future wired and wireless communication technologies (e.g., power line communication, cellular network, internet protocol networks, ZigBee, Wi-Fi, Worldwide Interoperability for Microwave Access, etc.). Also, advanced techniques for accessing the network and routing the information to the different nodes of the network will be required. In this chapter, we discuss smart-grid communication network and divide it into three tiers, i.e., home area network, neighborhood area network, and wide-area network. We present smart-grid communication technologies, standards, and protocols for the physical layer operations. We next discuss the medium access control (MAC) and network layer protocols of the smart-grid communication technologies. In the end, we present a case study for the implementation and performance evaluation of various smart-grid algorithms and communication infrastructure.

A quasi-orthogonal STBC design for SC-FDMA in LTE-advanced

21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2010

ABSTRACT In this paper, a class of quasi-orthogonal space-time block codes (Q-STBC) is proposed f... more ABSTRACT In this paper, a class of quasi-orthogonal space-time block codes (Q-STBC) is proposed for systems with 2 antennas and 3 time slots, where the orthogonal Alamouti code can not be applied due to the “odd symbol” problem inherited in the 3GPP frame structure. The proposed codes can achieve rate one and full diversity with lower complexity maximum likelihood detection. The design takes into consideration the signal power fluctuation and minimizes the potential peak-to-average ratio (PAPR) in the transmitted signals. The application to Single Carrier Frequency Division Multiple Access (SC-FDMA) has been investigated further. A transmission scheme is proposed to preserve the good PAPR property of SC-FDMA. In addition, linear and iterative decoding algorithms are proposed to simplify the receiver complexity. Simulations have been conducted to demonstrate the superior performance.

Location-Aware Spectrum and Power Allocation in Joint Cognitive Communication-Radar Networks

Proceedings of the 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2011

A novel approach to spectrum and power allocation is proposed for joint cognitive communication-r... more A novel approach to spectrum and power allocation is proposed for joint cognitive communication-radar networks, which aim at integrating cognitive radio (CR-o) and cognitive radar (CR-r) paradigms to achieve intelligent utilization of spectrum resources in wireless networks. This approach exploits the location information offered by CR-r combined with spectrum sensing capability of CR-o to aid spectrum and power allocation by minimizing harmful interference among neighboring devices. Such systems require both coexistence and sharing of perception of radio environment and radar scene. To offer better spectrum resource utilization, entropy of the received signal is employed in order to detect spectrum holes over the network topology. This entropy-based technique also demonstrates superior performance as compared to the conventional method based on energy detection. Simulation results indicate both throughput improvement and interference reduction among neighboring devices.

Peak-to-Average Ratio Constrained Demand-Side Management With Consumer's Preference in Residential Smart Grid

IEEE Journal of Selected Topics in Signal Processing, 2014

In a smart grid network, demand-side management plays a significant role in allowing consumers, i... more In a smart grid network, demand-side management plays a significant role in allowing consumers, incentivized by utilities, to manage their energy consumption. This can be done through shifting consumption to off-peak hours and thus reducing the peak-to-average ratio (PAR) of the electricity system. In this paper, we begin by proposing a demand-side energy consumption scheduling scheme for household appliances that considers a PAR constraint. An initial optimization problem is formulated to minimize the energy cost of the consumers through the determination of the optimal usage power and operation time of throttleable and shiftable appliances, respectively. We realize that the acceptance of consumers of these load management schemes is crucial to its success. Hence, we then introduce a multi-objective optimization problem which not only minimizes the energy cost but also minimizes the inconvenience posed to consumers. In addition to solving the proposed optimization problems in a centralized manner, two distributed algorithms for the initial and the multi-objective optimization problems are also proposed. Simulation results show that the proposed demand-side energy consumption schedule can provide an effective approach to reducing total energy costs while simultaneously considering PAR constraints and consumers' preferences.

Feasibility of using discriminate pricing schemes for energy trading in smart grid

2014 IEEE Global Communications Conference, 2014

This paper investigates the feasibility of using a discriminate pricing scheme to offset the inco... more This paper investigates the feasibility of using a discriminate pricing scheme to offset the inconvenience that is experienced by an energy user (EU) in trading its energy with an energy controller in smart grid. The main objective is to encourage EUs with small distributed energy resources (DERs), or with high sensitivity to their inconvenience, to take part in the energy trading via providing incentive to them with relatively higher payment at the same time as reducing the total cost to the energy controller. The proposed scheme is modeled through a two-stage Stackelberg game that describes the energy trading between a shared facility authority (SFA) and EUs in a smart community. A suitable cost function is proposed for the SFA to leverage the generation of discriminate pricing according to the inconvenience experienced by each EU. It is shown that the game has a unique sub-game perfect equilibrium (SPE), under the certain condition at which the SFA's total cost is minimized, and that each EU receives its best utility according to its associated inconvenience for the given price. A backward induction technique is used to derive a closed form expression for the price function at SPE, and thus the dependency of price on an EU's different decision parameters is explained for the studied system. Numerical examples are provided to show the beneficial properties of the proposed scheme. Index Terms-Smart grid, discriminate pricing, distributed energy resources, game theory, energy management.

Trading Delay for Distortion in One-Way Video Communication Over the Internet

IEEE Transactions on Circuits and Systems for Video Technology, 2016

We study the problem of one-way video communication in a single-source, multiple-destination scen... more We study the problem of one-way video communication in a single-source, multiple-destination scenario over the lossy Internet. Forward error correction (FEC) coding is commonly adopted for data protection in implementing loss-resilient video transmission systems. However, the burst packet losses over the Internet frequently degrade FEC performance and induce video quality deteriorations. To address the challenging problem, we propose a novel transmission scheme dubbed trading delay for distortion (TELFORD) that includes three components: 1) adaptive multidestination status estimation; 2) delay-constrained transmission rate assignment; and 3) differentiated FEC packet spreading. We analytically formulate and solve the problem of FEC packet allocation and scheduling to minimize the end-to-end video distortion. The proposed TELFORD is able to cope with multiple-destination scheduling separately. We conduct performance evaluation through semiphysical emulations in Exata using real-time H.264 video streaming. Experimental results show that TELFORD outperforms existing error control transmission schemes in improving the video peak signal-to-noise ratio and mitigating packet transmission impairments.

New High-Rate STBC With Good Dispersion Property

2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications

... NEW HIGH-RATE STBC WITH GOOD DISPERSION PROPERTY Yong Liang Guan Tjeng Thiang Tjhung Nanyang ... more

Energy Efficient Multicast Routing in Mobile Ad Hoc Networks

Lecture Notes in Computer Science, 2003

In this paper, we address the problem of multicast routing in mobile ad-hoc networks from the vie... more In this paper, we address the problem of multicast routing in mobile ad-hoc networks from the viewpoint of energy efficiency. In an ad-hoc wireless network, each node runs on a local energy source which has a limited energy life span. Thus, energy conservation is a critical issue in mobile ad-hoc networks. One approach for energy conservation is to establish routes that require lowest total energy consumption. This optimization problem is referred as the minimum-energy multicast routing problem (MEMRP). In this paper, propose new efficient heuristic algorithms for the construction of energyefficient multicast routes in mobile ad-hoc networks. These algorithms exploit the broadcast nature of the wireless channel, and address the need for energyefficient operations. Empirical studies show that our algorithms are able to achieve better performance than algorithms that have been developed for MEMRP.

Bi-Directional Multi-Antenna Relay Communications with Wireless Network Coding

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

In this paper, we consider a two-way or bidirectional communications system with a relay equipped... more In this paper, we consider a two-way or bidirectional communications system with a relay equipped with multiple antennas. We show that when the downlink channel state information is not known at the relay, the benefit of having additional antennas at the relay can only be obtained by using decode and forward (DF) but not amplify and forward (AF). The gain becomes significant when we employ transmit diversity together with wireless network coding. We also demonstrate how the performance of such system can be improved by performing antenna selection at the relay. Our results show that if downlink channel state information is known at the relay, network coding may not provide additional gain than simple antenna selection scheme.

Decentralized block diagonalization algorithms for distributed MIMO systems

International Symposium on Wireless and Pervasive Computing, 2011

Page 1. Decentralized Block Diagonalization Algorithms for Distributed MIMO Systems Mauricio Mora... more

Optimizing quasi-orthogonal STBC through group-constrained linear transformation

IEEE Global Telecommunications Conference, 2004. GLOBECOM '04.

In this paper, we first derive the generic algebraic structure of a Quasi-Orthogonal STBC (QO-STB... more In this paper, we first derive the generic algebraic structure of a Quasi-Orthogonal STBC (QO-STBC). Next we propose Group-Constrained Linear Transformation (GCLT) as a means to optimize the diversity and coding gains of a QO-STBC with square or rectangular QAM constellations. Compared with QO-STBC with constellation rotation (CR), we show that QO-STBC with GCLT requires only half the number of symbols for joint detection, hence lower maximum-likelihood decoding complexity. We also derive analytically the optimum GCLT parameters for QO-STBC with square QAM constellation. The optimized QO-STBCs with GCLT are able to achieve full transmit diversity, and have negligible performance loss compared with QO-STBCs with CR at the same code rate.

Construction of quasi orthogonal STBC with minimum decoding complexity

International Symposium onInformation Theory, 2004. ISIT 2004. Proceedings.

In this paper, we formulate the algebraic structure of Quasi-Orthogonal STBC with minimum decodin... more In this paper, we formulate the algebraic structure of Quasi-Orthogonal STBC with minimum decoding complexity (MDC-QOSTBC), whose maximum likelihood (ML) decoder only requires the joint detection of two real symbols, for any numbers of transmit antennas. We also propose a systematic method to construct an MDC-QOSTBC from an Orthogonal-STBC (O-STBC). The maximum code rate of the resultant MDC-QOSTBC is shown to be the same as that of the lower-order O-STBC used to construct it. We also find the optimum constellation rotation angle for the proposed MDC-QOSTBC construction to achieve full diversity and optimum coding gain. We can show that the proposed MDC-QOSTBC has more even power distribution over the transmit antennas, better scalability in adjusting the number of transmit antennas, and more superior decoding performance than the Coordinate Interleaved Orthogonal Design (CIOD) and Asymmetric CIOD.

Limited feedback for multi-antenna multi-user communications with Generalized Multi-Unitary Decomposition

2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, 2008

In this paper, we propose a decomposition method called Generalized Multi-Unitary Decomposition (... more

Channel Allocation in a Multiple Distributed Vehicular Users Using Game Theory

2010 IEEE 71st Vehicular Technology Conference, 2010

In this paper, we look into the channel allocation problem for a non-cooperative cognitive vehicu... more In this paper, we look into the channel allocation problem for a non-cooperative cognitive vehicular ad-hoc communication network with multiple communicating pairs distributed spatially apart. An algorithm which can search for all pure Nash Equilibrium (NE) solutions is presented. We study how the number of pure NEs grows when either the size of the network or the number of available channels gets higher. Myopic play of a game, in which the players take turn to choose its best response strategy, is a common approach to obtain one of these NE solutions, if the algorithm converges. However, we found that for myopic play of the game, the probability of convergence to the NE which has the desired best global utility is not guaranteed. We further propose two player ordering schemes to study how the probability of hitting the best global solution among all possible NEs is affected. We find that by allowing the node with the lowest "expected" utility to decide first increases the chance of hitting the NE solution with better utility value.

Unbalanced and Balanced 2-Group Decodable Spatial Multiplexing Code

2009 IEEE 70th Vehicular Technology Conference Fall, 2009

Spatial multiplexing code (SMC) has high transmission code rate but also high maximum likelihood ... more Spatial multiplexing code (SMC) has high transmission code rate but also high maximum likelihood (ML) decoding complexity. To overcome this disadvantage, we propose 2-group decodable SMC with full symbol-wise diversity for arbitrary number of transmit antennas. In this paper, unbalanced 2group decodable SMC is first constructed and used to construct balanced 2-group decodable SMC. The rates of both the unbalanced/balanced 2-group decodable SMCs approach Nt asymptotically when T Nt where Nt is the number of transmit antennas and T is the code length. To our best knowledge, this is the first time that 2-group decodable SMCs are constructed systematically.

Four-Node Relay Network with Bi-Directional Traffic Employing Wireless Network Coding with Pre-Cancellation

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

Network coding has the potential to improve the overall throughput of a network by combining diff... more Network coding has the potential to improve the overall throughput of a network by combining different streams of data and forwarding them. In wireless networks, the wireless channel provide an excellent medium for physical layer network coding as signals from different transmitters are combined automatically by the wireless channel. In such scenarios, it would be interesting to investigate protocols and algorithms which can optimally relay information. In this paper, we look at a four-node two-way or bidirectional relay network, and propose a relay protocol which can relay information efficiently in this network.

Beamforming matrix quantization with variable feedback rate

2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, 2008

We propose an improved beamforming matrix compression by Givens Rotation with the use of variable... more We propose an improved beamforming matrix compression by Givens Rotation with the use of variable feedback rate. The variable feedback rate means that the number of bits used to represent the quantized beamforming matrix is based on the value of the matrix. Compared with the fixed feedback rate scheme, the proposed method has better performance without additional feedback bandwidth.

Non-homogeneous distributed storage systems

2012 50th Annual Allerton Conference on Communication, Control, and Computing (Allerton), 2012

This paper describes a non-homogeneous distributed storage systems (DSS), where there is one supe... more This paper describes a non-homogeneous distributed storage systems (DSS), where there is one super node which has a larger storage size and higher reliability and availability than the other storage nodes. We propose three distributed storage schemes based on (k + 2, k) maximum distance separable (MDS) codes and non-MDS codes to show the efficiency of such non-homogeneous DSS in terms of repair efficiency and data availability. Our schemes achieve optimal bandwidth k+1 2 M k when repairing 1-node failure, but require only one fourth of the minimum required file size and can operate with a smaller field size leading to significant complexity reduction than traditional homogeneous DSS. Moreover, with non-MDS codes, our scheme can achieve an even smaller repair bandwidth of M 2k. Finally, we show that our schemes can increase the data availability by 10% than the traditional homogeneous DSS scheme. Index Terms-Exact-repair MDS codes, non-homogeneous DSS, minimum storage regenerating (MSR) codes.