EURASIP Journal on Wireless Communications and Networking, 2012
Spectrum sensing is a key technique in cognitive radio networks (CRNs), which enables cognitive r... more Spectrum sensing is a key technique in cognitive radio networks (CRNs), which enables cognitive radio nodes to detect the unused spectrum holes for dynamic spectrum access. In practice, only a small part of spectrum is occupied by the primary users. Too high sampling rate can cause immense computational costs and sensing problem. Based on sparse representation of signals in the frequency domain, it is possible to exploit compressed sensing to transfer the sampling burden to the digital signal processor. In this article, an effective spectrum sensing approach is proposed for CRNs, which enables cognitive radio nodes to sense the blind spectrum at a sub-Nyquist rate. Perfect reconstruction from fewer samples is achieved by a blind signal reconstruction algorithm which exploits p -norm (0 < p < 1) minimization instead of 1 or 1 / 2 mixed minimization that are commonly used in existing signal recovery schemes. Simulation results demonstrated that the p -norm spectrum reconstruction scheme can be used to break through the bandwidth barrier of existing sampling schemes in CRNs.
Graph theory is a traditional mathematical method to analyze computer networks, including intelli... more Graph theory is a traditional mathematical method to analyze computer networks, including intelligent wireless networks, such as ad hoc networks, sensor networks, and wireless mesh networks. Because of the variety of the network nodes and wireless links, conventional graph theory and set theory used to describe the element of the network (node and link) are not suitable to model the modern complex wireless networks. Recent research in weighted graph and random graph theories that place a weight on the links and a probability to decide the existence of the link or not is a further step to model the wireless network in a near real-life scenario. However, it lacks the ability to describe the properties of the network node. In this paper, a new mathematical tool, polychromatic sets (PS-sets), is introduced in modeling the complex wireless networks. PS-sets have the ability to describe the property of each element, which we believe will be a perfect tool to describe the network nodes and links of wireless networks. This paper demonstrates a scalable network modeling using PS-sets theory and a routing scheme based on this model. Evaluation results show that it is simple and scalable, and its performance is superior to other conventional routing schemes. The PS-sets theory could become a new tool in studying modern complex wireless networks.
2015 IEEE Symposium on Computers and Communication (ISCC), 2015
Future 5G networks have stringent end-user requirements on data rate and error performance. In or... more Future 5G networks have stringent end-user requirements on data rate and error performance. In order to satisfy these requirements, innovative wireless networking technologies and models need be researched. One particular example is the two-way relaying channel, which can have as much as 100% higher theoretical data rate than current systems where transmissions are arranged in an orthogonal manner. However, benefits of this model cannot be achieved without the application of proper relaying protocols. This paper proposes a novel protocol that directly addresses the problems of existing protocols of twoway relaying models, e.g. analogy network coding and physical network coding, and has improved performance. By combining direct and differential demodulation-forward schemes based on wireless channel qualities and signal to noise ratio, a new hybrid protocol is created. Theoretical analysis and numerical experiments show that the proposed solution has lower error rate than the existing ones, and can thus be applied to support future 5G networks.
Proceedings of the 10th International Conference on Mobile and Ubiquitous Multimedia - MUM '11, 2011
In this paper, we present a 3D indoor navigation service system based on smartphones. To achieve ... more In this paper, we present a 3D indoor navigation service system based on smartphones. To achieve an accurate indoor navigation system in a multi-storey building, it is necessary to determine the storey where the user is. By attaching an atmosphere pressure sensor on smartphones, the altitude information of the user can be obtained, and then, the storey where the user
Conference Record of the 1996 IEEE International Symposium on Electrical Insulation, 1996
In this paper, the charge accumulation process at microscopic interfaces in insulating materials ... more In this paper, the charge accumulation process at microscopic interfaces in insulating materials filled with inorganic fillers is analyzed by using a unit model. Dynamic equations of interfacial ionic charge accumulation are proposed by the authors. The charge accumulation and its regulations are proved by TSC test results obtained on silica filled EPDM samples
2009 IEEE International Symposium on IT in Medicine & Education, 2009
This paper presents the latest development of a mobile device to be used in wireless mesh network... more This paper presents the latest development of a mobile device to be used in wireless mesh networks for healthcare. The mobile device is capable of video streaming, Internet access, and voice over wireless networks. In addition, the optimisation techniques are applied to improve the network efficiency by multicast and stream the required videos based on the condition of network by
Wireless Communications and Mobile Computing, 2010
In the IEEE 802.11 wireless LAN (WLAN), the fundamental medium access control (MAC) mechanism---d... more In the IEEE 802.11 wireless LAN (WLAN), the fundamental medium access control (MAC) mechanism---distributed coordination function (DCF), only supports best-effort service, and is unaware of the quality-of-service (QoS). IEEE 802.11e enhanced distributed channel access (EDCA) supports service differentiation by differentiating contention parameters. This may introduce the problem of non-cooperative service differentiation. Hence, an incompletely cooperative EDCA (IC-EDCA) is proposed in this paper to solve the problem. In IC-EDCA, each node that is cooperative a priori adjusts its contention parameters (e.g., the contention window (CW)) adaptively to the estimated system state (e.g., the number of competing nodes of each service priority). To implement IC-EDCA in current WLAN nodes, a frame-analytic estimation algorithm is presented. Moreover, an analytical model is proposed to analyze the performance of IC-EDCA under saturation cases. Extensive simulations are also carried out to compare the performances of DCF, EDCA, incompletely cooperative game, and IC-EDCA, and to evaluate the accuracy of the proposed performance model. The simulation results show that IC-EDCA performs better than DCF, EDCA, and incompletely cooperative game in terms of system throughput or QoS, and that the proposed analytical model is valid. dependent packet-level tuning (ChaPLeT), adaptive EDCF (AEDCF), and adaptive fair EDCF, three representative enhanced methods . ChaPLeT focuses on improving service differentiation by configuring three selected parameters, i.e., fragmentation threshold, persistence factor, and defer countdown, based on monitored channel conditions. However, ChaPLeT does not consider the impact of network load. AEDCF focuses on improving throughput
M-health system has been defined as combination of "mobile computing, medical sensor, and co... more M-health system has been defined as combination of "mobile computing, medical sensor, and communications technologies" for health-care. As a mature short-range wireless technology, Bluetooth has been used in healthcare areas to improve the flexibility for patients, medical doctors or nurses to access the health service. This paper addresses the Bluetooth connectivity issues on a specific implementation of a mobile diabetes management system.
2009 WRI International Conference on Communications and Mobile Computing, 2009
Wireless mesh nodes equipping multi-radio interfaces on each node and using multi-channel for tra... more Wireless mesh nodes equipping multi-radio interfaces on each node and using multi-channel for transmission can greatly enhance the network performance. In this paper, a genetic algorithm, genetic tabu search, was presented to solve the channel assignment problem. The algorithm was evaluated by simulation on NS2 and compared with greedy and multi-radio unification protocol algorithms. Simulation results showed that the performance
International Journal of Distance Education Technologies, 2011
In this paper, a video streaming system for education based on wireless mesh network is proposed.... more In this paper, a video streaming system for education based on wireless mesh network is proposed. Wireless mesh network is a self-organizing, self-managing and reliable intelligent network which allows educators to deploy a network quickly whenever there is a need. Video streaming plays an important role in this system for multimedia data transmission. This new system adopts the scalable video
Metro systems are one of the most important transportation systems in people's lives. Due to the ... more Metro systems are one of the most important transportation systems in people's lives. Due to the huge amount of energy it consumes every day, highly-efficient operation of a metro system will lead to significant energy savings. In this paper, a new integrated Energy-efficient Operation Methodology (EOM) for metro systems is proposed and validated. Compared with other energy saving methods, EOM does not incur additional cost. In addition, it provides solutions to the frequent disturbance problems in the metro systems. EOM can be divided into two parts: Timetable Optimization (TO) and Compensational Driving Strategy Algorithm (CDSA). First, to get a basic energy-saving effect, a genetic algorithm is used to modify the dwell time of each stop to obtain the most optimal energy-efficient timetable. Then, in order to save additional energy when disturbances happen, a novel CDSA algorithm is formulated and proposed based on the foregoing method. To validate the correctness and effectiveness of the energy-savings possible with EOM, a real case of Shanghai Metro Line One (SMLO) is studied, where EOM was applied. The result shows that a significant amount of energy can be saved by using EOM.
EURASIP Journal on Wireless Communications and Networking, 2012
Spectrum sensing is a key technique in cognitive radio networks (CRNs), which enables cognitive r... more Spectrum sensing is a key technique in cognitive radio networks (CRNs), which enables cognitive radio nodes to detect the unused spectrum holes for dynamic spectrum access. In practice, only a small part of spectrum is occupied by the primary users. Too high sampling rate can cause immense computational costs and sensing problem. Based on sparse representation of signals in the frequency domain, it is possible to exploit compressed sensing to transfer the sampling burden to the digital signal processor. In this article, an effective spectrum sensing approach is proposed for CRNs, which enables cognitive radio nodes to sense the blind spectrum at a sub-Nyquist rate. Perfect reconstruction from fewer samples is achieved by a blind signal reconstruction algorithm which exploits p -norm (0 < p < 1) minimization instead of 1 or 1 / 2 mixed minimization that are commonly used in existing signal recovery schemes. Simulation results demonstrated that the p -norm spectrum reconstruction scheme can be used to break through the bandwidth barrier of existing sampling schemes in CRNs.
Graph theory is a traditional mathematical method to analyze computer networks, including intelli... more Graph theory is a traditional mathematical method to analyze computer networks, including intelligent wireless networks, such as ad hoc networks, sensor networks, and wireless mesh networks. Because of the variety of the network nodes and wireless links, conventional graph theory and set theory used to describe the element of the network (node and link) are not suitable to model the modern complex wireless networks. Recent research in weighted graph and random graph theories that place a weight on the links and a probability to decide the existence of the link or not is a further step to model the wireless network in a near real-life scenario. However, it lacks the ability to describe the properties of the network node. In this paper, a new mathematical tool, polychromatic sets (PS-sets), is introduced in modeling the complex wireless networks. PS-sets have the ability to describe the property of each element, which we believe will be a perfect tool to describe the network nodes and links of wireless networks. This paper demonstrates a scalable network modeling using PS-sets theory and a routing scheme based on this model. Evaluation results show that it is simple and scalable, and its performance is superior to other conventional routing schemes. The PS-sets theory could become a new tool in studying modern complex wireless networks.
2015 IEEE Symposium on Computers and Communication (ISCC), 2015
Future 5G networks have stringent end-user requirements on data rate and error performance. In or... more Future 5G networks have stringent end-user requirements on data rate and error performance. In order to satisfy these requirements, innovative wireless networking technologies and models need be researched. One particular example is the two-way relaying channel, which can have as much as 100% higher theoretical data rate than current systems where transmissions are arranged in an orthogonal manner. However, benefits of this model cannot be achieved without the application of proper relaying protocols. This paper proposes a novel protocol that directly addresses the problems of existing protocols of twoway relaying models, e.g. analogy network coding and physical network coding, and has improved performance. By combining direct and differential demodulation-forward schemes based on wireless channel qualities and signal to noise ratio, a new hybrid protocol is created. Theoretical analysis and numerical experiments show that the proposed solution has lower error rate than the existing ones, and can thus be applied to support future 5G networks.
Proceedings of the 10th International Conference on Mobile and Ubiquitous Multimedia - MUM '11, 2011
In this paper, we present a 3D indoor navigation service system based on smartphones. To achieve ... more In this paper, we present a 3D indoor navigation service system based on smartphones. To achieve an accurate indoor navigation system in a multi-storey building, it is necessary to determine the storey where the user is. By attaching an atmosphere pressure sensor on smartphones, the altitude information of the user can be obtained, and then, the storey where the user
Conference Record of the 1996 IEEE International Symposium on Electrical Insulation, 1996
In this paper, the charge accumulation process at microscopic interfaces in insulating materials ... more In this paper, the charge accumulation process at microscopic interfaces in insulating materials filled with inorganic fillers is analyzed by using a unit model. Dynamic equations of interfacial ionic charge accumulation are proposed by the authors. The charge accumulation and its regulations are proved by TSC test results obtained on silica filled EPDM samples
2009 IEEE International Symposium on IT in Medicine & Education, 2009
This paper presents the latest development of a mobile device to be used in wireless mesh network... more This paper presents the latest development of a mobile device to be used in wireless mesh networks for healthcare. The mobile device is capable of video streaming, Internet access, and voice over wireless networks. In addition, the optimisation techniques are applied to improve the network efficiency by multicast and stream the required videos based on the condition of network by
Wireless Communications and Mobile Computing, 2010
In the IEEE 802.11 wireless LAN (WLAN), the fundamental medium access control (MAC) mechanism---d... more In the IEEE 802.11 wireless LAN (WLAN), the fundamental medium access control (MAC) mechanism---distributed coordination function (DCF), only supports best-effort service, and is unaware of the quality-of-service (QoS). IEEE 802.11e enhanced distributed channel access (EDCA) supports service differentiation by differentiating contention parameters. This may introduce the problem of non-cooperative service differentiation. Hence, an incompletely cooperative EDCA (IC-EDCA) is proposed in this paper to solve the problem. In IC-EDCA, each node that is cooperative a priori adjusts its contention parameters (e.g., the contention window (CW)) adaptively to the estimated system state (e.g., the number of competing nodes of each service priority). To implement IC-EDCA in current WLAN nodes, a frame-analytic estimation algorithm is presented. Moreover, an analytical model is proposed to analyze the performance of IC-EDCA under saturation cases. Extensive simulations are also carried out to compare the performances of DCF, EDCA, incompletely cooperative game, and IC-EDCA, and to evaluate the accuracy of the proposed performance model. The simulation results show that IC-EDCA performs better than DCF, EDCA, and incompletely cooperative game in terms of system throughput or QoS, and that the proposed analytical model is valid. dependent packet-level tuning (ChaPLeT), adaptive EDCF (AEDCF), and adaptive fair EDCF, three representative enhanced methods . ChaPLeT focuses on improving service differentiation by configuring three selected parameters, i.e., fragmentation threshold, persistence factor, and defer countdown, based on monitored channel conditions. However, ChaPLeT does not consider the impact of network load. AEDCF focuses on improving throughput
M-health system has been defined as combination of "mobile computing, medical sensor, and co... more M-health system has been defined as combination of "mobile computing, medical sensor, and communications technologies" for health-care. As a mature short-range wireless technology, Bluetooth has been used in healthcare areas to improve the flexibility for patients, medical doctors or nurses to access the health service. This paper addresses the Bluetooth connectivity issues on a specific implementation of a mobile diabetes management system.
2009 WRI International Conference on Communications and Mobile Computing, 2009
Wireless mesh nodes equipping multi-radio interfaces on each node and using multi-channel for tra... more Wireless mesh nodes equipping multi-radio interfaces on each node and using multi-channel for transmission can greatly enhance the network performance. In this paper, a genetic algorithm, genetic tabu search, was presented to solve the channel assignment problem. The algorithm was evaluated by simulation on NS2 and compared with greedy and multi-radio unification protocol algorithms. Simulation results showed that the performance
International Journal of Distance Education Technologies, 2011
In this paper, a video streaming system for education based on wireless mesh network is proposed.... more In this paper, a video streaming system for education based on wireless mesh network is proposed. Wireless mesh network is a self-organizing, self-managing and reliable intelligent network which allows educators to deploy a network quickly whenever there is a need. Video streaming plays an important role in this system for multimedia data transmission. This new system adopts the scalable video
Metro systems are one of the most important transportation systems in people's lives. Due to the ... more Metro systems are one of the most important transportation systems in people's lives. Due to the huge amount of energy it consumes every day, highly-efficient operation of a metro system will lead to significant energy savings. In this paper, a new integrated Energy-efficient Operation Methodology (EOM) for metro systems is proposed and validated. Compared with other energy saving methods, EOM does not incur additional cost. In addition, it provides solutions to the frequent disturbance problems in the metro systems. EOM can be divided into two parts: Timetable Optimization (TO) and Compensational Driving Strategy Algorithm (CDSA). First, to get a basic energy-saving effect, a genetic algorithm is used to modify the dwell time of each stop to obtain the most optimal energy-efficient timetable. Then, in order to save additional energy when disturbances happen, a novel CDSA algorithm is formulated and proposed based on the foregoing method. To validate the correctness and effectiveness of the energy-savings possible with EOM, a real case of Shanghai Metro Line One (SMLO) is studied, where EOM was applied. The result shows that a significant amount of energy can be saved by using EOM.
Uploads
Papers by Xinheng Wang