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Search Results: 1 - 10 of 120106 matches for " Xiumin Wang "
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Statistical Precoder Design for Space-Time-Frequency Block Codes in Multiuser MISO-MC-CDMA Systems
Xiaoming Chen,Xiumin Wang
Mathematics , 2014,
Abstract: In this paper, we present a space-time-frequency joint block coding (STFBC) scheme to exploit the essential space-time-frequency degrees of freedom of multiuser MISO-MC-CDMA systems. Specifically, we use a series of orthogonal random codes to spread the space time code over several sub-carriers to obtain multi-diversity gains, while multiuser parallel transmission is applied over the same sub-carriers by making use of multiple orthogonal code channels. Furthermore, to improve the system performance, we put forward to linear precoding to the predetermined orthogonal STFBC, including transmitting directions selection and power allocation over these directions. We propose a precoder design method by making use of channel statistical information in time domain based on the Kronecker correlation model for the channels, so feedback amount can be decreased largely in multi-carrier systems. In addition, we give the performance analysis from the perspectives of diversity order and coding gain, respectively. Moreover, through asymptotic analysis, we derive some simple precoder design methods, while guaranteeing a good performance. Finally, numerical results validate our theoretical claims.
Partial Third-Party Information Exchange with Network Coding
Xiumin Wang,Chau Yuen
Mathematics , 2013,
Abstract: In this paper, we consider the problem of exchanging channel state information in a wireless network such that a subset of the clients can obtain the complete channel state information of all the links in the network. We first derive the minimum number of required transmissions for such partial third-party information exchange problem. We then design an optimal transmission scheme by determining the number of packets that each client should send, and designing a deterministic encoding strategy such that the subset of clients can acquire complete channel state information of the network with minimal number of transmissions. Numerical results show that network coding can efficiently reduce the number of transmissions, even with only pairwise encoding.
Network Coded Wireless Cooperative Multicast with Minimum Transmission Cost
Xiumin Wang,Jin Wang,Shukui Zhang
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/614206
Abstract: We study multicasting over wireless lossy links. Instead of downloading all the data from the source node, we allow the destination nodes themselves to locally exchange the packets, as local communication within a cluster achieves higher packet reception probability with less transmission cost. However, when shall we stop the transmission from the source node? If the source stops too early, the destination nodes locally cannot reconstruct all the original packets, while if the source stops too late, the benefit of cooperative data exchange cannot be fully exploited. In this paper, we propose a network coded hybrid source and cooperative exchange scheme to determine when to stop the source sending and start the exchange process, so as to minimize the total transmission cost. For the case when the clusters are predefined, we derive the expected total transmission cost with our hybrid scheme. Our theoretical results show that under a special condition, the source node should keep sending the packets until all the destinations get the complete information. For the case when the clusters are not predefined, we propose a cluster division algorithm such that the destination nodes within each cluster can conduct data exchange locally with energy efficiency. Finally, simulation results demonstrate the effectiveness of the proposed scheme.
Data Dissemination in Wireless Sensor Networks with Network Coding
Wang Xiumin,Wang Jianping,Xu Yinlong
EURASIP Journal on Wireless Communications and Networking , 2010,
Abstract: In wireless sensor networks (WSNs), it is often necessary to update the software running on sensors, which requires reliable dissemination of large data objects to each sensor with energy efficiency. During data dissemination, due to sleep scheduling designed for energy efficiency, some sensors may not receive some packets at some time slots. In the meantime, due to the unreliability of wireless communication, a sensor may not successfully receive a packet even when it is in the active mode. Thus, retransmission of such packets to those sensors is necessary, which consumes more energy and increases the delay of data dissemination cycle. In this paper, we propose a network coding-based approach in data dissemination such that data dissemination can be accomplished at the earliest time. Thus, less energy is consumed and the delay can be decreased. The impact of packet loss probability and the sleep probability of sensors on the network coding gain is analyzed. A threshold is also given to decide whether the current sleep scheduling is effective on energy saving in data dissemination process or not. Simulation results demonstrate the effectiveness and scalability of the proposed work.
Data Dissemination in Wireless Sensor Networks with Network Coding
Xiumin Wang,Jianping Wang,Yinlong Xu
EURASIP Journal on Wireless Communications and Networking , 2010, DOI: 10.1155/2010/465915
Abstract: In wireless sensor networks (WSNs), it is often necessary to update the software running on sensors, which requires reliable dissemination of large data objects to each sensor with energy efficiency. During data dissemination, due to sleep scheduling designed for energy efficiency, some sensors may not receive some packets at some time slots. In the meantime, due to the unreliability of wireless communication, a sensor may not successfully receive a packet even when it is in the active mode. Thus, retransmission of such packets to those sensors is necessary, which consumes more energy and increases the delay of data dissemination cycle. In this paper, we propose a network coding-based approach in data dissemination such that data dissemination can be accomplished at the earliest time. Thus, less energy is consumed and the delay can be decreased. The impact of packet loss probability and the sleep probability of sensors on the network coding gain is analyzed. A threshold is also given to decide whether the current sleep scheduling is effective on energy saving in data dissemination process or not. Simulation results demonstrate the effectiveness and scalability of the proposed work.
A Prediction Model of China Population Growth
Hao Zhang,Chao Wang,Xiumin Zhang
Computer and Information Science , 2009, DOI: 10.5539/cis.v1n2p27
Abstract: In this article, we develop a prediction model of China population growth, and notice that the modified index curve is a sort of curve that possesses the growth limit K in the statistics, which is the same with the problem of China population growth. Considering influences of urbanization, population aging and sex proportion, we adopt and improve the modified index model, and add some coefficients to adjust the mathematical equation according to the data. The computation results show that in a short period, the population quantity will increase slowly and approach a fixed value, and in a long term, with the influence of population aging, some factors will put up periodic fluctuations.
Farmers Involved in the Production of Agricultural Standardization Factors Analysis
Qin Luo,Xiumin Wu,Hao Wang
Journal of Agricultural Science , 2011, DOI: 10.5539/jas.v3n3p251
Abstract: This paper, uses the survey data of 104 households in the city of Sichuan by the method of Logistic regression analysis, has analysised factors of the farmers who involved in agricultural standardization of production or not. Research shows that the cognitive level of standardization, awareness of pesticides’ hazards, their own age and family numbers have significantly influenced on the famers who involved in standardization of agricultural production. Then there are some recommends for solving.
Joint Rate Selection and Wireless Network Coding for Time Critical Applications
Xiumin Wang,Chau Yuen,Yinlong Xu
Computer Science , 2011,
Abstract: In this paper, we dynamically select the transmission rate and design wireless network coding to improve the quality of services such as delay for time critical applications. With low transmission rate, and hence longer transmission range, more packets may be encoded together, which increases the coding opportunity. However, low transmission rate may incur extra transmission delay, which is intolerable for time critical applications. We design a novel joint rate selection and wireless network coding (RSNC) scheme with delay constraint, so as to minimize the total number of packets that miss their deadlines at the destination nodes. We prove that the proposed problem is NPhard, and propose a novel graph model and transmission metric which consider both the heterogenous transmission rates and the packet deadline constraints during the graph construction. Using the graph model, we mathematically formulate the problem and design an efficient algorithm to determine the transmission rate and coding strategy for each transmission. Finally, simulation results demonstrate the superiority of the RSNC scheme.
Coding based Data Broadcasting for Time Critical Applications with Rate Adaptation
Xiumin Wang,Chau Yuen,Yinlong Xu
Computer Science , 2013,
Abstract: In this paper, we dynamically select the transmission rate and design wireless network coding to improve the quality of services such as delay for time critical applications. In a network coded system, with low transmission rate and hence longer transmission range, more packets may be encoded, which increases the coding opportunity. However, low transmission rate may incur extra transmission delay, which is intolerable for time critical applications. We design a novel joint rate selection and wireless network coding (RSNC) scheme with delay constraint, so as to maximize the total benefit (where we can define the benefit based on the priority or importance of a packet for example) of the packets that are successfully received at the destinations without missing their deadlines. We prove that the proposed problem is NP-hard, and propose a novel graph model to mathematically formulate the problem. For the general case, we propose a transmission metric and design an efficient algorithm to determine the transmission rate and coding strategy for each transmission. For a special case when all delay constraints are the same, we study the pairwise coding and present a polynomial time pairwise coding algorithm that achieves an approximation ratio of 1 - 1/e to the optimal pairwise coding solution, where e is the base of the natural logarithm. Finally, simulation results demonstrate the superiority of the proposed RSNC scheme.
Energy-Efficient Optimization for Wireless Information and Power Transfer in Large-Scale MIMO Systems Employing Energy Beamforming
Xiaoming Chen,Xiumin Wang,Xianfu Chen
Computer Science , 2013,
Abstract: In this letter, we consider a large-scale multiple-input multiple-output (MIMO) system where the receiver should harvest energy from the transmitter by wireless power transfer to support its wireless information transmission. The energy beamforming in the large-scale MIMO system is utilized to address the challenging problem of long-distance wireless power transfer. Furthermore, considering the limitation of the power in such a system, this letter focuses on the maximization of the energy efficiency of information transmission (bit per Joule) while satisfying the quality-of-service (QoS) requirement, i.e. delay constraint, by jointly optimizing transfer duration and transmit power. By solving the optimization problem, we derive an energy-efficient resource allocation scheme. Numerical results validate the effectiveness of the proposed scheme.
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