Q. Gao

ADAL: A distributed range-free localization algorithm based on a mobile beacon for wireless sensor networks

Wireless sensor networks (WSNs) is emerging as a key tool for data acquisition in many applications, and localization algorithms of the sensors have a vital importance due to the intrinsic characteristics of this type of networks. The objective of this paper is to propose an algorithm of range-free localization for WSNs using a mobile beacon node equipped with a rotary directional antenna. The azimuthally defined area localization algorithm (ADAL) is executed in each sensor node and is based only on the analysis of the information received from the mobile beacon node, therefore is energy efficient and contributes to extend the lifetime of the sensor network. Additionally the proposed algorithm has the advantage of being simple and economical. The simulation results show that the proposed algorithm is a practical, effective and accurate method to localize sensor nodes in a WSN.

A range-free localization algorithm for wireless sensor networks based on unmanned aerial vehicles

Wireless sensor networks (WSNs) is emerging as a key tool for data acquisition in many applications, and localization algorithms of the sensors have a vital importance due to the intrinsic characteristics of this type of networks. The objective of this paper is to propose an algorithm of range-free localization for WSNs using an unmanned aerial vehicle (UAV) equipped with a rotary directional antenna. This algorithm, denominated as the azimuthally defined area localization algorithm (ADAL), is executed in each sensor node and is based only on the analysis of the information received from the UAV, therefore is energy efficient and contributes to extend the lifetime of the sensor network. Additionally the proposed algorithm has the advantage of being simple and economical. The simulation results show that the proposed algorithm is a practical, effective and accurate method for sensor nodes location in a WSN.

A distributed range-free localization algorithm for wireless sensor networks based on a mobile robot

Wireless sensor networks (WSNs) is emerging as a key tool for data acquisition in many applications, and localization algorithms of the sensors have a vital importance due to the intrinsic characteristics of this type of networks. The objective of this paper is to propose an algorithm of range-free localization for WSNs using a mobile robot equipped with a rotary directional antenna. This algorithm, denominated as the azimuthally defined area localization algorithm (ADAL), is executed in each sensor node and is based only on the analysis of the information received from the mobile robot, therefore is energy efficient and contributes to extend the lifetime of the sensor network. Additionally the proposed algorithm has the advantage of being simple and economical. The simulation results show that the proposed algorithm is a practical, effective and accurate method to localize sensor nodes in a WSN.

Energy efficient cooperative MIMO with Idle nodes in cluster based wireless sensor networks

Energy saving is a very important design consideration in wireless sensor networks. In cluster based wireless sensor networks, the energy could be saved when the nodes in a cluster that have data to transmit participate in cooperative Multiple Input Multiple Output (MIMO). In this paper, by making the idle nodes, that have no data to transmit, participate in the cooperative MIMO it is found that much more energy could be saved. The number of the idle nodes that participate in the cooperative MIMO can be optimized to minimize the total energy consumption. It is also found that the optimal number of all the nodes participating in cooperative communication does not vary with the number of nodes that have data to transmit in the cluster. The proposition is proved mathematically. The influence of long-haul distance and modulation constellation size on the total energy consumption is investigated in this paper as well.

Energy-efficient cooperative communication with multi-relay contention and power allocation

In this paper, we propose an energy-efficient multi-relay contention and power allocation scheme. A new cooperative MAC scheme is introduced, in which multiple contention slots are employed for relay candidates to contend. To guarantee the energy efficiency under a required data rate, relay contention criteria is designed to select energy-efficient relay candidates. Transmit power then is optimally allocated among source and successfully contended relays to minimize the transmitting energy consumption. We also investigate how the number of relay contention slots affects the system performance. Simulation results show that our proposed scheme saves significant amount of energy compared with direct (non-cooperative) scheme.

Analysis of Multiple Contention Slots MAC Protocol in MIMO Ad Hoc Networks

Wireless ad hoc networks have been employed in pervasive computing, rescue and so on. Employing MIMO spatial multiplexing in ad hoc networks, multiple links in the same neighborhood could coexist and multiple RTS/CTS contention slots are required to contest medium. The RTS/CTS contention is a severe overhead that mitigates the performance improvement. The transmission power, which determines the number of neighboring nodes, also affects the RTS/CTS contention efficiency. In this paper, the transmission power and contention slots number are optimized jointly to improve transport throughput based on a proposed analytical model.

Iterative receiver with joint channel estimation and decoding in LTE downlink

In this paper, an iterative receiver using joint channel estimation and channel decoding is proposed for LTE downlink. In each iterative process, a modified LMMSE estimator is adopted to estimate the channel gain based on pilots as well as signals fed back from Turbo decoder. In contrast to a traditional LMMSE estimator, the modified estimator can make more precise channel estimation because a smaller spacing interpolation is performed with the help of feedback signals. The estimator and the decoder provide each other more accurate information in an iterative way, thus the performance of the receiver is improved. Three distribution patterns of the signals fed back from Turbo decoder with different density is compared, and the one with medium density is demonstrated to be the best by simulation results. To reduce the computational complexity of the receiver, cyclic redundancy check (CRC) is used to early stop the iteration. Simulation is done according to LTE physical layer specifications and the results show that the iterative receiver can provide about 50% accuracy improvement compared with a non-iterative receiver when SNR is 10dB. At the same time, the iterative receivers computational complexity is in the same order of magnitude as the non-iterative receiver.

Long-term rain attenuation prediction for Ka-Band link over Venezuela

The determination of the slant-path long-term rain attenuation has been formally characterized on the ITU Recommendation P. 618–8, using an empirical statistical model, suitable for frequencies up to 55 GHz. For the purpose of applying this method on the study of the rain phenomena over the Venezuelan region, different Matlab scripts have been written, aiming to automate the calculation process, iterating the attenuation prediction over the area of interest. The implementation was done based on the VENESAT-I telecommunication system. Results yield with the expected values, and the Matlab implementation has been made available for free use and distribution.

A routing scheme based on subarea mobile service in wireless sensor networks

The mobility has been shown to be beneficial to improve the performance of wireless sensor networks. In this paper, a new routing scheme based on subarea mobile service is proposed. According to the number of mobile nodes in the network, the area of network is divided into multiple subareas equally. In each subarea, there is one mobile node to relay the data of static nodes. Based on Nearest Neighbor Algorithm, each mobile node plans the moving path in its own subarea. The simulation result shows that under the proposed routing scheme, the throughput of network could be increased, the average delay and delay jitter could be reduced.

A pricing scheme to maximize social welfare in communication networks

In this paper, we analyze switching from the current flat-rate Internet pricing to adopt usage-based pricing schemes. Even if flat rate pricing is one of the main reasons for the success of the Internet, the only way to prevent network congestion, differentiate services and maximizes social welfare is to adopt usage-based pricing schemes. Our scheme is highly related to an optimal congestion and cost-sharing pricing scheme for multiclass services applied to communication networks developed by Yezekael Hayel, Bruno Tuffin and design a pricing scheme that maximizes the social welfare which is the total gross value minus the total expected delay cost.