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Yang G.,Hubei Engineering University | Yang G.,Hubei Research and Design Institute of Agro Machinery Engineering | Gan X.,Hubei Engineering University | Gan X.,Hubei Research and Design Institute of Agro Machinery Engineering | And 3 more authors.
Key Engineering Materials | Year: 2014

In wireless sensor networks where the volume and energy of nodes are limited by batteries, which are difficult or prohibitively expensive to replace or recharge in the most of its application scenarios, so improving energy efficiency has very important significance. Cooperative beamforming forms virtual antenna arrays by multiple adjacent wireless sensor nodes, which improves the signal strength at the receiver and reduces the energy consumption of the transmitter by multiplexing gain and interference management. In this paper, the problem of energy consumption optimization for cooperative beamforming in wireless sensor networks was studied. First, considering both amplifier energy consumption and circuit energy consumption, energy consumption models for both broadcast phase and cooperative beamforming phase was presented. Then, we propose a two-step optimization to minimize the total energy consumption by optimizing the modulation parameter and the number of cooperative nodes. We simulate the total energy consumption for various transmission distances, modulation parameters, path losses and the number of cooperative nodes. The numerical results show that, for different system parameters, selecting the optimal modulation parameter and the optimal number of cooperative nodes can reduce total energy consumption and improve energy efficiency. © (2014) Trans Tech Publications, Switzerland.


Yang G.,Hubei Research and Design Institute of Agro Machinery Engineering | Zhu S.,Hubei Research and Design Institute of Agro Machinery Engineering | Quan R.,Hubei Research and Design Institute of Agro Machinery Engineering | Ma Z.,Hubei Research and Design Institute of Agro Machinery Engineering
Key Engineering Materials | Year: 2014

As the key technologies such as wireless communication, sensor continues to mature, wireless sensor networks has become a domestic and foreign focus of research in the field of wireless networks. The main work of the thesis is to implement ZigBee wireless sensor networking, using open source protocol FreakZ On the base of existing hardware. WSN hardware node consists of 32-bit microprocessor STM32F102CB based on ARM Cortex-M3 kernel and AT86RF212 radio transceiver; the software platform uses a lightweight multi-tasking operating system Contiki and open source protocol stack called FreakZ following ZigBee protocol specification, for networking wireless networks nodes. The paper presents the system architecture of WSN networking and its hardware components, software architecture and data transmission and reception processes of the networks. Using FreakZ protocol stack under the Contiki operating system on the base of the existing hardware platform, the network nodes information and topology displayed on the HyperTerminal indicates the success of WSN networking by using FreakZ protocol. © (2014) Trans Tech Publications, Switzerland.

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