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This paper presents a new learning-based framework to jointly solve equalization and symbol detection problems in orthogonal frequency division multiplexing systems with quadrature amplitude modulation. The framework utilizes extreme learning machine (ELM), a recent addition to the class of supervised learning algorithms, to achieve fast training, high performance, and low error rates. The proposed ELM scheme employs infinitely differentiable nonlinear activation functions in least-square solution to learn the channel response, which is the equalization part. In addition to equalization, ELM performs symbol detection. Existing learning-based schemes require an additional symbol slicer for the symbol detection. The proposed framework does not experience training bottleneck imposed by gradient descent-based approaches. Simulation results show that the proposed framework outperforms other learning-based equalizers in terms of symbol error rate and training speeds. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes the use of equalization concepts in frequency domain that exploit the frequency domain channel matrix to combat inter-carrier interference (ICI) instead of inter-symbol interference (ISI) in 5.9GHz Dedicated Short Range Communications (DSRC) systems. The physical layer (PHY) of DSRC is currently being developed by work group of IEEE 802.11p. The conventional system currently assumes static channel characteristics. Channel tracking schemes were investigated and the Viterbi-aided channel estimation scheme was proposed for DSRC systems that did not explicitly exploit the ICI components caused by the time-varying channels. The performance of the DSRC system is investigated for a time-varying channel using a conventional DSRC model, a decision-directed (Viterbi-aided) channel estimation model, and the frequency-domain equalization design. It is shown that the DSRC system with the frequency-domain equalization achieves a considerable performance enhancement compared to both the conventional and the Viterbi-aided channel estimation schemes in terms of both packet error rate (PER) and bit error rate (BER) at relatively high and low velocities. [Copyright &y& Elsevier]

Abstract: In this paper, a design of a new object-oriented simulation environment and graphical user interface (GUI) for versatile orthogonal frequency division multiplexing (OFDM) systems is presented. This is achieved using high-level design, parallelism and usability for the simulation environment. GUI interface can serve as a learning/research tool for students or practiced professionals to investigate particular designs. It is evident that OFDM systems intended to be used in dynamic environments must be tested under various conditions in order to be designed for optimality. Hence, a simulation design is proposed coupling the GUI, parallelism, and high-level object-oriented design techniques to be beneficial to the researcher. A high-level design and GUI layouts of the proposed simulator is shown in details. Important OFDM parameters needed for reconfiguration of transmitter components, channel condition parameters, and receiver components are discussed. In addition, this paper provides a simple technique to implement simulation partitioning for increased parallel performance of reconfigurable object-oriented OFDM simulators. This simple technique applies to scenarios where there is disproportionate simulation duration between different OFDM configurations. It is shown to decrease total simulation time considerably. [Copyright &y& Elsevier]

IEEE 802.15.4, commonly known as ZigBee, is a Media Access Control (MAC) and physical layer standard specifically designed for short range wireless communication where low rate, low power, and low bandwidth are required. This makes ZigBee an ideal choice when it comes to sensor networks for monitoring data collection and/or triggering process responses. However, these very characteristics bring into question ZigBee's ability to perform reliably in harsh environments. This paper thoroughly explains the experimental testbed setup and execution to demonstrate ZigBee's performance in several practical applications. This testbed is capable of measuring the minimum, maximum, and average received signal strength indicator (RSSI), bit error rate (BER), packet error rate (PER), packet loss rate (PLR), and the bit error locations. Results show that ZigBee has the potential capabilities to be used in all four tested environments. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present a study of the dedicated short range communications (DSRC) receiver performance under varying signal to noise ratio, velocity, symbol durations and packet lengths. Conventional channel estimation, which is used in IEEE 802.11a, assumes static channel characteristics for the entire packet duration. That is found to be infeasible for high velocity DSRC applications. Simulation results show that the packet-error-rate increases with the increase in relative velocity. Viterbi decoding substantially improves the performance, but the sensitivity to Doppler shift still exists. Analysis and simulation results show that extending the symbol duration or increasing packet length results in an increase of the packet-error-rate. These results may serve as benchmarks for future DSRC channel estimation methods. [Copyright &y& Elsevier]

Dedicated short range communication is proposed for vehicle to vehicle communications to learn about significant events in the network from neighboring vehicles. However, these neighbors may be malicious and report incorrect events in order to take advantage of the system. The malicious nodes may also provide incorrect recommendations about their peers in order to exert a stronger influence on the receiver's decision. Incorrect information and malicious nodes render the system unreliable for safety and emergency applications. In order to correctly identify the events as well as malicious nodes, a novel trust framework is proposed in this paper that studies all aspects of the trust in connected vehicle (CV) to CV communications. The nodes iteratively learn about the environment from received messages and then update the trust values of their neighbors. Nodes are classified on the basis of their trust values and reported events are also classified as true and false. Nodes advertise their recommendation about trusted and malicious neighbors. The proposed framework allows nodes to identify and filter recommendations from malicious nodes, and to discern true events. The performance of the proposed framework is evaluated experimentally using false and true positive rates, event detection probability and trust computation error. The proposed framework identifies malicious nodes and true events with high probability of more than 0.92 while keeping the trust computation error below 0.03. [ABSTRACT FROM PUBLISHER]

Communication systems are needed to integrate generated power from wind farms with the electrical grid. This paper provides a comprehensive review of available communication technologies, protocols and objectives related to wind energy and electrical grid integration. This paper summarizes the communication system solutions for wind generation. A major obstacle is an absence of unified communication architectures and standards. [ABSTRACT FROM PUBLISHER]