Applied Mechanics and Materials Vols. 321-324

Abstract: Body sensor networks(BSNs) are emerging cyberphysical systems that promise to improve quality of life through improved healthcare ,independent living for the elderly ,and reduced healthcare costs .In the BSN’s clients oriented family healthcare ,the methods of data storage and reading are important to data processing in BSN . This paper mainly studies the methods of real-time data storage in a BSN’s intelligent terminal based Android through the analysis of the client module’s architecture in a BSN .And an application model is finally designed to meet the need of mobile healthcare system’s data storage and reading .The application model is suitable for a BSN oriented family healthcare .Through testing this application model ,it indicates that this application model makes users more convenient to manage their medical data.

Abstract: In order to solve the difficulty of calling a taxi for urban residents, and reduce taxi no-load rate for taxi drivers, an Urban-Taxi accurate call service platform based on information self-matching was designed and realized by using wireless communication and combination positioning technologies. This platform can achieve real-time monitoring and management of the entire service area. By using a terminal, a passenger can book the nearest no-load taxi and wait for loading. Meanwhile, a taxi driver can use his or her terminal to get passenger’s information who wants to take a taxi. This approach simplifies calling process of passengers, matches passengers and no-load taxis intelligently, optimizes passengers travel experience, and reduces taxis no-load rate.

Abstract: Orthogonal frequency division multiplexing (OFDM) is a kind of highly transmission technology. It has been taken more and more attention in many ways. In this paper it mainly discussed the simulation process and several interpolation algorithms in OFDM system. Using computer we simulate the interpolation algorithms in OFDM channel estimation. Through the simulation results we compare the advantage and disadvantage of the interpolation algorithms. At last we can use the conclusion to choose the correct interpolation algorithms in OFDM channel estimation.

Abstract: The market potential of mobile point of sale (POS) service is attractive to the mobile network operators, while the traffic challenges caused by heavy traffic is becoming a critical issue to the operators. In order to guarantee the Quality of Service (QoS) and make best use of the existing network, it is important to model the traffic of mobile POS service. A tree-structured modeling method is presented in the paper, which can be used to model the traffic of mobile POS service as well as other interactive M2M services, such as remote medical services. The modeling method is a combination of the layered modeling method used in traditional H2H communications and the transaction tree modeling method used in bank trade. As another main point, a specific traffic model of mobile POS service is given in the paper. There are five parameters in the traffic model, including request packet size, response packet size, the interval between request and response, the interval between two requests, and the transmission probability. After counting the packet length of each message, calculating the average length, analyzing the effect of difference between the actual and average length on the cellular network, we find that all the request type of mobile POS service could be simplified as the average length. Further on, a curve-fitting method is used to obtain the distribution of the intervals. All the data used in the modeling are collected from the traffic of real network. The QoS attributes assumption of mobile POS service including the maximum accessing user number, the packet loss rate and the end-to-end delay is given in the article and is validated by the simulation using the specific model of mobile POS service provided in the paper. The assumption is consistent with the simulation result, and is proved to be reasonable. The results can be used as a reference when implementing mobile POS service in cellular network.

Abstract: Energy efficiency is a major concern for mesh nodes with limited power supply. So STDMA(spatial time division multiple access) is applied to reduce node’s power consumption in mesh networks. However, the energy cost was still high for solar panel applying with STDMA, due to the fixed slots and numerous start times of nodes. A VF-STDMA(variable frame in STDMA) is proposed based on STDMA protocol. The VF-STDMA dynamically changes the frame size and assigns timeslots to each link according to the network data flows. The start times are reduced by recombining slots. Finally, the optimum routing is obtained through a cross-layer mechanism covering physical layer, MAC layer and network layer. The results show that the algorithms improve energy efficiency as well as decrease energy consumption of solar panel.

Abstract: With the development of wireless technology, wireless network bandwidth is increasingly high require.OFDM modulation technique can be used to more fully utilize the available bandwidth.The paper studied the important role of the cyclic prefix in OFDM.We get the simulation figure when delay spread exceeds the cyclic prefix.Simulation results show that when cyclic prefix accounted 20%,the power loss is less than l dB,and information rate loss of up to 20%.But inserting a cyclic prefix can eliminate the influence of the inter-carrier caused by the inter-symbol interference and the inter-carrier caused by multipath interference.

Abstract: Wireless Mesh Network (WMN) is able to extend the coverage of the network infrastructure by multi-hop wireless connections between APs. However, full potentialities and limits of this new technology have still to be explored. In this paper, we design an experimental testbed to analyze the characterization of Channel Selection and Multi-hops in Wireless Mesh Network, we believe that the data collected by our experiments may be of interest to network designers who want to know the effective capabilities of a WMN before investing on its deployment.

Abstract: This work proposes a CRC-aided K-best sphere decoding scheme to improve the performance of lattice codes. The generator of the lattice is designed as to be an upper triangular, which is naturally suited for sphere decoding. When the K is sufficiently large, the naïve K-best sphere decoding can approach the lower bound of block error rate (BLER) of maximum likelihood (ML). Therefore, the proposed scheme can outperforms the naïve K-best sphere decoding with the assistance of CRC code.

Abstract: One of the major problems while dealing with underwater acoustic communication (UWAC) is the occurrence of unwanted multipath having long delay spreads. Higher probability of reflections (from wavy sea surface, uneven sea bottom, other obstacles, etc.) and refraction of sound are the main causes of these grievous multipath signals. Multipath effects further offer severe degradation in the packet (s) and mutilation of entire signal in terms of inter-symbolic interference (ISI) is occurred. During last decade, multicarrier modulation in terms of OFDM was considered as one of the viable solutions to mitigate the multipath effect and provide high-rate communication. In this article, we are performing the practical evaluation of Zero-Padded Orthogonal Frequency Division Multiplexing (ZP-OFDM) based communication system. The data using various packet structures are used to demonstrate the effectiveness of ZP-OFDM scheme in the flat multipath channel of the water pool of acoustic lab, Harbin Engineering University. Satisfactory performance results are obtained even within high noisy environment. These results suggest that ZP-OFDM is a viable choice for high-rate communications over multipath induced underwater channels.

Abstract: In this paper, a Turbo codes and Rake received mixed algorithm in multipath fading environment is proposed to solve the problems in signal reception in a fading environment of the mobile communication system. Compared to the traditional multi-path reception methods, the advantage of the algorithm can significantly improve system performance; reduce the system error rate by approximately 2.5dB. Moreover, the performance of the system will be improved a lot if the antenna power is equal. Firstly a mixed algorithm in AWGN channel and multipath fading channel is introduced and derived theoretically and then a computer simulation is carried out and the impact of various parameters on network performance is anglicized. The results show that the algorithm can effectively reduce the effects of multipath fading environment on the transmission power attenuation, lower bit error rate, and improve the effectiveness to resistance to multipath fading significantly.