Optimal pilots design for frequency offsets and channel estimation in OFDM modulated single frequency networks

Optimal pilot design and placement for both the frequency offsets and channel estimation in Orthogonal Frequency-Division Multiplexing modulated Single Frequency Network are treated.Unlike the conventional frequency-domain filter-based algorithms,the proposed pilot of each transmitter can always be demodulated at the receiver even if the received pilots of multiple transmitters are totally overlapped.Although the channel state information is needed in designing the proposed pilot for carrier frequency offset(CFO)estimation,the performance of the proposed CFO estimation is robust to the channel estimation error.The optimal pilot as well as the Least-Squares(LS)channel estimator is also proposed,and the pilot for channel estimation is always a constant-modulus.A joint frequency offset and channel estimation scheme is also proposed,and the transmitters can adaptively optimize their pilots in the successive transmissions using the estimation results feedback in the former transmission.Simulation results demonstrate the performance of the proposed algorithm in terms of frequency offset and channel estimation accuracies.Since multiple copies of the same information can be received at each receiver,some combining technologies such as equal gain combining(EGC)or maximal ratio combining(MRC)can be applied at the receiver to improve the receiving diversity gain.Numerical results show that in a scenario of two transmitters with a Signal-to-Noise Ratio of 20 dB,the Bit Error Rate(BER)of1.5×10-4(or 1×10-4)can be obtained at the receiver using EGC(or MRC),and this BER performance can be improved to be 4×10-6for EGC(or 2×10-6for MRC)by considering three co-receiver transmitters.     

Optimal resource allocation for transmission diversity in multi-radio access networks： a coevolutionary genetic algorithm approach

The next generation wireless communication systems aim at supporting enhanced diversified network access and data transmission abilities via the cooperative integration and unified management of various radio access technologies(RATs).The resource allocation is the core component leading the network system and mobile terminals to the service robustness and performance maximization.In this paper,a numeric optimization model for optimizing terminals’transmission power and allocated RAT bandwidth for maximizing system capacity is proposed with the focal consideration of the multi-radio transmission diversity for parallel transmission through multiple links from diferent RATs,and diferent terminal characteristics on RAT supports.Also,we design a centralized and periodic scheduling algorithm including an improved coevolutionary genetic algorithm for efciently solving the optimization problem.Simulation results demonstrate that our propose algorithm can distinctly enhance the system performance and improve the computational efciency.     

Technological Gap： The Education Case of the State of Puebla,Mexico

The teaching-learning process may have several obstacles; one of those would be a cultural situation of students but also the ICT （information and communication technologies） resource distribution per children. When we refer to cultural situation, we mean the language or dialect that they speak. In the state of Puebla, Mexico, there are primary schools in which courses are taught to students who do not speak Spanish and they only speak their own dialect. On the other hand, the use of information and communication technologies in primary schools in Puebla is a fact but a main concern in schools is that the languages in which are operated is Spanish. The present article will also deal with the distribution of enciclomedia sets per children population in the 217 communities of the state of Puebla. To analyze this situation, we find that turns out to be very important and with a negative effect on both the implementation and acceptance of a multimedia program in these schools, generating a technological gap between students. The government efforts are being decimated because of this cultural divide prevalent in many communities in the state of Puebla, Mexico.     

A Channel Model for Underground Sensor Networks in the Mixture of Crude Oil,Water and Soil

Future enhanced oil recovery technology can greatly benefit from the wireless sensor networks to effectively operate in underground oil reservoirs. In such a case, millimeter scale sensor nodes with antennas at the same scale have to be deployed in the confined underground oil reservoir fractures. This necessitates the sensor nodes to be operating in the THz frequency range. In this paper, the propagation based on electromagnetic （EM） waves in the Terahertz band （0.1-120.0 THz） through a crude oil/water mixture and soil medium is analyzed in order to explore its applicability in underground oil reservoir assessments. The developed model evaluates the total path loss and the absorption loss that an EM wave experiences when propagating through the crude oil/water mixture and soil medium. Our results show that sensors can communicate successfully for distances up to 1 cm. Furthermore, we have determined the existence of two transmission bands, in which the path loss is below 100 dB. Among those, the frequency window, which provides the best performance, is determined as 70 THz to 85 THz. Different path and absorption loss schemes are considered, which suggests that the 70 THz to 85 THz band is suitable for sensor communications in a medium of crude oil/water mixture and soil.     

Spatial Data Mining to Support Environmental Management and Decision Making--A Case Study in Brazil

The growth of geo-technologies and the development of methods for spatial data collection have resulted in large spatial data repositories that require techniques for spatial information extraction, in order to transform raw data into useful previously unknown information. However, due to the high complexity of spatial data mining, the need for spatial relationship comprehension and its characteristics, efforts have been directed towards improving algorithms in order to provide an increase of performance and quality of results. Likewise, several issues have been addressed to spatial data mining, including environmental management, which is the focus of this paper. The main original contribution of this work is the demonstration of spatial data mining using a novel algorithm with a multi-relational approach that was applied to a database related to water resource from a certain region of S~o Paulo State, Brazil, and the discussion about obtained results. Some characteristics involving the location of water resources and the profile of who is administering the water exploration were discovered and discussed.     

A Novel Matlab-Based Underwater Acoustic Channel Simulator

An accurate modeling of the UAC （underwater acoustic channel） can facilitate the development of an efficient architecture for an UAM （underwater acoustic modem）. The performance comparison of different architectures can be performed rapidly and at a low cost in a simulation environment, compared to testing the modems in sea water. This article presents the development and utilization of an underwater acoustic channel simulator. The simulator can be used by a communications engineer in characterizing the time variability of the physical channel＇s parameters or by a hardware engineer in designing an underwater acoustic modem. This tool is programmed in Matlab and is based on the algorithms Bounce and Bellhop. The input parameters of these algorithms must be saved in text files after a specific template and are cumbersome to process manually. To streamline the modeling of an UAC and the simulation of various communication algorithms the simulator automatically creates the input files based on key parameters entered by the user, hiding the algorithmic dependent ones and allows a quick visualization of the simulation results with a few routines specially created. The use of this simulator is emphasized with results obtained from the design of a low-power UAM for long-term monitoring activities.     

UHF Propagation Parameters to Support Wireless Sensor Networks for Onboard Trains

This paper reports numerical results for the characterization of the propagation channel in a train. Since the availability of a train to carry out measurements is not always easy, particularly when many changes must be done, a simulation tool provides a useful and reliable mean for the evaluation of the propagation characteristics of this complex and highly fluctuating channel. In order to benefit from previous results, the various existing softwares for complex electromagnetic fields environments simulations were fully searched and one that seems best suited has been retained for these computations. The results presented here are original, preliminaries and our approach provides a basis for study the propagation of waves in a very complex environment consisting of different electromagnetic fields like a train.     

Pareto optimal time-frequency resource allocation for selfish wireless cooperative multicast networks

In selfish wireless cooperative multicast networks （WCMNs）, a source node wants to achieve the optimal benefit （i.e., rate gain）, while the relaying nodes are willing to get fairness rewards （i.e., rate gains） from the source for the cooperative relaying. In this paper, we implement these two different objectives for the source and the relays through the Pareto optimal resource allocation. Define the cooperative strategy of a node as the fraction of a data-frame that it is willing to contribute to its cooperative partners. Consider the rational decision made by one node will definitely affect its cooperative partners＇ choice. Then, we can formulate this resource sharing problem as a Nash bargaining problem （NBP）, and the Nash bargaining solution （NBS） to the NBP encapsulates the Pareto optimality naturally. Finally, to enable the nodes to be capable of computing the NBS cooperative strategies rapidly as the wireless channel changes, we propose a fast particle swarm optimizer （PSO） algorithm to search for the NBS. Simulation results show that the two specified objectives of the source and the relays can be implemented in the Pareto optimal sense, i.e., the source can achieve a significant performance gain in comparison with direct multicast and the relays can get a fair reward by the source according to the level of contribution it has made to improve the performance of the source.     

Algorithms for checking channel passing in web service choreography

Web service choreography describes global mod- els of service interactions among a set of participants. For an interaction to be executed, the participants must know the required channel（s） used in the interaction, otherwise the ex- ecution will get stuck. Since channels are composed dynami- cally, the initial channel set of each participant is often insuf- ficient to meet the requirements. It is the responsibility of the participants to pass required channels owned （known） by one to others. Since service choreography may involve many par- ticipants and complex channel constraints, it is hard for de- signers to specify channel passing in a choreography exactly as required. We address the problem of checking whether a service choreography lacks channels or has redundant chan- nels, and how to automatically generate channel passing based on interaction flows of the service choreography in the case of channel absence. Concretely, we propose a sim- ple language Chorc, a channel interaction sub-language for modeling the channel passing aspect of service choreography. Based on the formal operational semantics of Chore, the algo- rithms for static checking of service choreography and gen- erating channel passing are also studied, and the complexity results of algorithms are discussed. Moreover, some illus- trated service choreography examples are presented to show how to formalize and analyze service choreography with channel passing in Chorc.     

Interference cancellation aided channel estimation for OFDM/OQAM system

Abstract Orthogonal frequency division multiplexing offset-QAM （OFDM/OQAM） is a promising multi- carrier transmission technique for its merits such as operating without cyclic prefix （CP） and flexibility of introducing well time-frequency localized pulse shapes. However, under dispersive channel condition, the intrinsic inter-symbol and inter-carrier interference arises in OFDM/OQAM system. Especially, the surrounding data symbols will cause interferences to the pilot symbols, leading to channel estimation error and degradation of system performance. In this paper, an efficient pilot structure and a channel estimation method are proposed for OFDM/OQAM system. The basic principal is to rebuild the transmitted symbols around the considered pilot position through pre-decision, then calculate and cancel the interference from the received signal. Analysis and simulation results show that the proposed scheme outperforms conventional ones with respect to both channel estimation accuracy and bit error rate （BER） performance while with less pilot consumption.     

Performance analysis of three multi-radio access control policies in heterogeneous wireless networks

Access control policy in wireless networks has a significant impact on QoS satisfaction and resource utilization efficiency. The design of access control policy in heterogeneous wireless networks （HWNs） becomes more challenging especially for the heterogeneous multiple access protocols of each radio network. In this paper, a Markov model is proposed to analyze the performance of three access control policies for HWNs. The first policy is the optimal radio access technology （O-RAT） selection, where the incoming traffic always tries to access one network with the maximum service rate before admission. The second policy intends to allocate the same data to all networks. And the traffic will leave the system if it is accomplished first by one of these networks, which is formulated as the aggregated multi-radio access （A-MRA） technology. The third policy is named the parallel multi-radio access （P-MRA） transmission, in which the incoming traffic is split into different networks. The traffic is served with the sum of the service rates provided by overall networks. Numerical and simulate results show the effectiveness of our analytical framework and the performance gain of the three access control policies. As illustrated with some representative results, the P-MRA policy shows superior performance gain to the other two policies independent on the specific parameters of the different multiple access protocols due to the multiplexing gain.     

信道估计误差下多用户MIMO／OFDM下行系统自适应传输

以系统总速率最大化为目标，提出在非理想信道信息情形下基于空分复用的多用户MIMO／OFDM下行系统的自适应资源分配方案，并满足用户的QoS要求。该方案首先根据用户信道估计误差模型和用户QoS对用户进行子载波分配，然后在各个子载波上进行功率和比特分配。仿真结果表明，该方案相对静态分配方案可获得更大的总速率，而且对信道估计错误更加强健，可应用到信道信息不确定的实际系统中。     

Resource allocation for physical-layer security in OFDMAdownlinkwith imperfect CSI

We investigate the problem of resource allocation in a downlink orthogonal frequency-division multiple access (OFDMA) broadband network with an eavesdropper under the condition that both legitimate users and the eavesdropper are with imperfect channel state information (CSI). We consider three kinds of imperfect CSI: (1) noise and channel estimation errors, (2) feedback delay and channel prediction, and (3) limited feedback channel capacity, where quantized CSI is studied using rate-distortion theory because it can be used to establish an informationtheoretic lower bound on the capacity of the feedback channel. The problem is formulated as joint power and subcarrier allocation to optimize the maximum-minimum (max-min) fairness criterion over the users’ secrecy rate. The problem considered is a mixed integer nonlinear programming problem. To reduce the complexity, we propose a two-step suboptimal algorithm that separately performs power and subcarrier allocation. For a given subcarrier assignment, optimal power allocation is achieved by developing an algorithm of polynomial computational complexity. Numerical results show that our proposed algorithm can approximate the optimal solution.     

Towards estimating computer users＇ mood from interaction behaviour with keyboard and mouse

The purpose of this exploratory research was to study the relationship between the mood of computer users and their use of keyboard and mouse to examine the possibility of creating a generic or individualized mood measure. To examine this, a field study （n = 26） and a controlled study （n = 16） were conducted. In the field study, interaction data and self-reported mood measurements were collected during normal PC use over several days. In the controlled study, participants worked on a programming task while listening to high or low arousing background music. Besides subjective mood measurement, galvanic skin response （GSR） data was also collected. Results found no generic relationship between the interaction data and the mood data. However, the re- suits of the studies found significant average correlations be- tween mood measurement and personalized regression models based on keyboard and mouse interaction data. Together the results suggest that individualized mood prediction is pos- sible from interaction behaviour with keyboard and mouse.     

A 2.4 GHz low power CMOS transceiver for LR-WPAN applications

A 2.4 GHz low power transceiver for low-rate wireless personal area network(LR-WPAN)applications is presented.The optimized low-IF receiver consists of a novel current reuse RF front-end with an inductor-less-load balun LNA and quadrature mixer,and an adaptive analog baseband to reduce power and area.It achieves-94 dBm of sensitivity,-9 dBm of IIP3 and 28 dBc of image rejection.The phase-locked loop based direct phase modulated transmitter is proposed to reduce power and deliver a+3 dBm output power.The phase noise of the low power frequency synthesizer with current reuse stacked LC-VCO achieves-107.8 dBc/Hz at 1 MHz offset.An ultra-low power nonvolatile memory is used to store configuration data and save power.The chip is implemented in a 0.18μm CMOS process,and the area is less than 2.8 mm2.The transceiver consumes only 10.98 mW in the receiving mode and 13.32 mW in the transmitting mode.     

Wideband Rectangular and Circular Microstrip Antennas Loaded with U-Shaped Slot

In this paper, a dual frequency resonance antenna is analysed by introducing U-shaped slot in a rectangular and circular patch, the results in terms of return loss, input impedance and radiation pattern are given. It is observed that various antenna parameters are obtained as a function of frequency for different value of slot length and width; it is easy to adjust the upper and the lower band by varying these different antenna parameters. The coaxial feed is used to excite the patch antenna. All the theoretical results using Matlab are compared with the simulated results obtained from Ansoft HFSS which are in close agreement. Furthermore, comparative study between our results and those available in the literature is done and showed to be in good agreement.     

Normalized Efficient Routing Protocol for WSN

WSNs （wireless sensor networks） consist of thousands of tiny nodes having the capability of sensing, computation, and wireless communications. Unfortunately these devices are limited energy devices, that is means we must save energy as much as possible, to increase network life time as long as possible. In this paper we introduce NEER--normalized energy efficient routing protocol that increases network life time through switching between AODV protocol that depends on request-reply routing, and MRPC that depends on residual battery in routing.     

From IP to Start-up： Building a Robust Life Science Incubator

An incubator is an organization that supports new ventures to grow and survive during the early stages. Mainly dedicated to information technology, life science may appear to be the next hot spot for incubators. Are there stabilized good practices？ Are the business models in information technology and in life science comparable when it goes to start-ups＇ incubation？ Leveraging our experience as practitioner in this field and using an inductive methodology, this paper tends to propose simple principles to help build robust incubators in life science, and to contribute to disseminate an entrepreneurial approach through an industry still dominated by blue chips.     

Power System Stability Improvement by Using STATCOM with POC ＆ Excitation Controller

This paper presents the model of a static synchronous condenser （STATCOM） which is controlled externally by a newly designed power oscillation controller （POC） for the improvements of power system stability and damping effect of an on line power system. The proposed POC consists of two controllers （power oscillation damping ＆ proportional integral derivative PID ＆ POD）. PID parameters have been optimized by Zigler Necles close loop tuning method. Machine excitation has been controller by using excitation controller as required. Both single phase and three phase faults has been considered in the research. In this paper, a power system network is considered which is simulated in the phasor simulation method ＆ the network is simulated in three steps： without STATCOM, with STATCOM but no externally controlled, STATCOM with POC. Simulation result shows that without STATCOM, the system parameters become unstable during faults. When STATCOM is imposed in the network, then system parameters become stable. Again, when STATCOM is controlled externally by POC controllers, then system voltage ＆ power becomes stable in faster way then without controller It has been observed that the STATCOM ratings are only 20 MVA with controllers and 200 MVA without controllers. Therefore, STATCOM with POC controllers are more effective to enhance the voltage stability and increases power transmission capacity of a power system. So STATCOM with POC ＆ excitation controllers, the system performance is greatly enhanced.