Tuan-Duc Nguyen

Impact of Transmission Synchronization Error and Cooperative Reception Techniques on the Performance of Cooperative MIMO Systems

Wireless sensor networks where neighbor nodes can cooperate both at transmission and reception by using the cooperative multi-input multi-output (MIMO) technique are considered. Space-time diversity gain can be exploited to reduce the transmission energy consumption which is very important for average and long range transmission in wireless sensor network (WSN). However, differing from classical MIMO systems, cooperative systems suffer from the lack of synchronization between distributed nodes and the additive noise in the cooperative reception. At the cooperative transmission side, we investigate the effect of transmission synchronization error which generates inter-symbol interference (ISI), decreases the desired signal amplitude and makes the channel state information (CSI) more difficult to be estimated by the receiver. At the cooperative reception side, two strategies of wireless transmission techniques which are energy efficient and have good performance are also presented. The simulation of a cooperative MIMO system using Alamouti and Tarokh space-time block codes (STBC) over Rayleigh fading channels presents a performance degradation in the presence of transmission synchronization error and additional noise of cooperative reception techniques. For a small synchronization error range at cooperative transmission and a reasonable amplification factor in reception, the degradation is negligible and the cooperative MIMO performance is rather good.

Energy-Efficient Cooperative Techniques for Infrastructure-to-Vehicle Communications

In wireless distributed networks, cooperative relay and cooperative multiple-input-multiple-output (MIMO) techniques can be used to exploit the spatial and temporal diversity gains to increase the performance or reduce the transmission energy consumption. The energy efficiency of cooperative MIMO and relay techniques is then very useful for the infrastructure-to-vehicle (I2V) and infrastructure-to-infrastructure (I2I) communications in intelligent transport system (ITS) networks, where the energy consumption of wireless nodes embedded on road infrastructure is constrained. In this paper, applications of cooperation between nodes to ITS networks are proposed, and the performance and the energy consumption of cooperative relay and cooperative MIMO are investigated and compared with the traditional multihop technique. The comparison between these cooperative techniques helps us choose the optimal cooperative strategy in terms of energy consumption for energy-constrained road infrastructure networks in ITS applications.

Improving the performance of mobile data collecting systems for electricity meter reading using Wireless Sensor Network

Nowadays, Automatic Meter Reading (AMR) systems have been studied and largely exploited in many developed countries, using different communication techniques such as PLC, Wi-Fi, Telephone Line, etc. However, recent researches have shown that collecting data using Wireless Sensor Network (WSN) is the future technology for AMR system. In fact, researchers have implemented the technique gathering data using WSN. Nevertheless, this kind of network has different characteristics compared with the traditional WSN. This work proposes the metering network topology corresponding to the household distribution in most of developing countries. Then, it presents the data collection method for this topology and points out the essential of Mobile Data Collector (MDC) for this network. Finally, it shows the effect of MDC speed on the reliability of electricity data collection using NS2 simulation. The simulation results indicate that the proposed data collection method has an improvement over the traditional MDC data collection using ZigBee wireless devices.

Performance analysis of spectrum sharing-based multi-hop decode-and-forward relay networks under interference constraints

The closed-form expressions for outage probability, bit error rate, and ergodic capacity of spectrum sharing-based multi-hop decode-and-forward (DF) relay networks in non-identical Rayleigh fading channels are derived. Utilizing these precise and tractable analytical formulas, we can study the impact of key network parameters on the performance of cognitive multi-hop relay networks under interference constraints. The analytical expressions are verified by Monte-Carlo simulations.

Towards residential smart grid: A practical design of wireless sensor network and Mini-Web server based low cost home energy monitoring system

Power grid is reaching its limitations, smart-grid technology will be necessary in the near future to increase the efficiency and reliability. Wireless sensor network (WSN) is a potential solution to develop smart grid system in residential area. In this paper, we describe a WSN and mini-Web Server based low cost energy monitoring system which enables residents monitor and control their domestic energy consumption of appliances to optimize their energy cost. Real time power consumption data of home area systems can be accessed by energy provider; based on this data, online pricing can be applied reduce Peak to Average Ratio of energy consumption. The system can support the development of smart grid which delivers electricity from suppliers to consumers based on two-way communications. The advantages of our system are low cost, robustness and simple deployment.

Cooperative MISO and Relay Comparison in Energy Constrained WSNs

In wireless distributed networks where multiple antennas can not be installed in one wireless node, cooperative relay and cooperative Multi-Input Multi-Output (MIMO) techniques can be used to exploit the spatial and temporal diversity gain in order to reduce the energy consumption. The simplicity and the energy efficiency of cooperative Multi-Input Single-Output (MISO) and relay techniques is very useful for the energy constrained Wireless Sensor Networks (WSN). In this paper, the performance and the energy consumption of the cooperative MISO and relay techniques are investigated over a Rayleigh fading channel. If under ideal conditions cooperative MISO has been proved to be better than relay, the latter is a better solution when transmission synchronization errors occur. The comparison between these two cooperative techniques helps us to choose the optimal cooperative strategy for energy constrained WSN applications.

On the design of energy efficient environment monitoring station and data collection network based on ubiquitous wireless sensor networks

In the context of ubiquitous wireless sensor network, this paper presents a framework for wireless sensor networks (WSNs) designed to observe impacts of climate change in crop fields. We propose a system architecture for ubiquitous WSNs for monitoring automatically and continuously in real-time. A prototype system includes two base stations and several sensor nodes which are powered by solar cell are designed and implemented. Climatic parameters from sensor nodes are sent via WSN to the base station, while base station communicates with remote data server center through GPRS/3G network. By using multiple methods of communication, it could enable monitor areas where not in GPRS/3G coverage. With advantages of low-cost and ubiquitous monitoring, the system can be applied widely in agriculture in developing countries like Vietnam. Power consumption estimation and NS-2 simulation results prove the energy efficient of environment stations and data collection networks.

Energy efficient cooperative communication techniques for Intelligent Transport System

In wireless distributed networks, cooperative relay and cooperative Multi-Input Multi-Output (MIMO) techniques can be used to exploit the spatial and temporal diversity gain in order to increase the performance or reduce the transmission energy consumption. The energy efficiency of cooperative MIMO and relay techniques is then very useful for the Infrastructure to Vehicle (I2V) and Infrastructure to Infrastructure (I2I) communications in Intelligent Transport Systems (ITS) networks where the energy consumption of wireless nodes embedded on road infrastructure is constrained. In this paper, applications of cooperation between nodes to ITS networks are proposed and the performance and the energy consumption of cooperative relay and cooperative MIMO are investigated in comparison with the traditional multi-hop technique. The comparison between these cooperative techniques helps us to choose the optimal cooperative strategy in terms of energy consumption for energy constrained road infrastructure networks in ITS applications.

Energy efficient wireless sensor network and low power consumption station design for an urban water level monitoring system

In the context of wireless sensor networks (WSN), a design of an energy efficient wireless data collecting network and a low power water level monitoring station have been proposed in this paper. Different low power consumption sub-Ghz wireless modules have been compared in this paper, and a most efficient wireless module have been selected in order to design a wireless sensor network. This power efficient wireless sensor network have been designed to connect to many water level monitoring stations and transmit its data to a remote centre. In order to ensure a longterm operation in environment without the grid power supply, solar power supply have been selected and a low power consumption design of a water level monitoring station is also proposed. Finally, the power consumption of the proposed station with wireless sensor network module has been calculated to prove the energy efficiency. With the advantage of a low power consumption and low cost design, the proposed wireless sensor network and water level monitoring station can be applied widely in urban environment in developing countries like Vietnam.

Ubiquitous sensor network for development of climate change monitoring system based on solar power supply

This paper presents a framework for wireless sensor networks (WSNs) designed to observe impacts of climate change in crop fields. We propose a system architecture for ubiquitous WSNs for monitoring automatically and continuously in realtime. A prototype system includes two base stations and several sensor nodes which are powered by solar cell are designed and implemented. Climatic parameters from sensor nodes are sent via WSN to the base station, while base station communicates with remote data server center through GPRS network. By using multiple methods of communication, it could enable monitor areas where not in GPRS coverage. With advantages of low-cost and ubiquitous monitoring, the system can be applied widely in agriculture in developing countries like Vietnam.