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An electric network frequency (ENF) signal can be found in multimedia recordings due to propagation from the power grid. There a variety of applications based on ENF signal use, such as video and audio stream synchronization, and origin determination of multimedia recordings. In this paper, we propose the use of ENF to synchronize real-time audio streams from different, non-synchronized sound devices,...
Interference cancellation (IC) has been proposed to improve bandwidth utilization for the majority of modern wireless networks. We claim that the conventional model for IC residual error, which is that the residual error power is simply a fraction of the power of the packet being cancelled, is overly simplified. In this paper, we evaluate the practical residual error of IC with spread MSK modulation...
A mutual-capacitance touch-sensing architecture and a system that enables concurrent usage of multiple active styluses having different properties such as color, thickness, shape, etc., are developed and verified with use of an existing touch controller [1]. An extension of the architecture to handle wireless active styluses is also developed and verified with an analog front-end (AFE) IC.
In this paper, asynchronous sensor localization using time-of-arrival (TOA) measurements is studied. Accurate TOA-based localization requires perfect timing synchronization between the source and anchor nodes. In asynchronous networks, the anchor nodes are assumed to be synchronized, while the clock of the source node needs be synchronized with those of the anchor nodes. Although synchronization and...
Radio interferometric positioning systems (RIPS) are recently proposed for low-complexity and high-accuracy localization. However, the original RIPS involves four nodes (two transmitters and two receivers) for a ranging session, and requires stringent time synchronization upon two receivers. In this paper, an asynchronous radio interferometric positioning system (ARIPS) is developed with larger positioning...
Constructive Interference (CI) proposed in the existing work (e.g., A-MAC [1], Glossy [2]) may degrade the packet reception performance in terms of Packet Reception Ratio (PRR) and Received Signal Strength Indication (RSSI). The packet reception performance of a set of nodes transmitting simultaneously might be no better than that of any single node transmitting individually. In this paper, we redefine...
To determine the physical location of an acoustic or wireless emitter or source localization is commonly encountered in sensor networks which are attempting to locate and track an emitter or source of the signal. In this paper, we propose a bandwidth efficient method of TDOA (Time Difference of Arrival) computation when the signals of opportunity use multicarrier modulation. Simulation results show...
This paper is concerned with localization in wireless sensor networks (WSNs). We propose a novel localization algorithm based beamforming. The performed localization algorithm is adopted for a typical communication model in WSNs involving two clusters of sensors at both transmitter and receiver sides of the communication link. The set of collaborative sensor nodes located at the transmit cluster could...
Wireless Audio Sensor Networks (WASNs) can provide event detection, object tracking and emergency response through cooperative audio sensor nodes. Effective collaboration of audio sensors requires precise synchronization among audio streams. Some researches have been done on the timestamp mechanism based on time synchronization ignoring propagation delay and many other researches have focused on the...
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...
In this paper, a new type of collaboration in wireless sensor networks (WSN) is suggested that exploits array processing algorithms to improve the reception of a signal. For receive collaboration, the transmission power during intra-cluster transmissions decreases at the expense of increasing the inter-cluster communications. It is shown that, as a result of using receive collaboration, the destination...
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...
The next generation of wireless networks (e.g., Long Term Evolution (LTE) and WiMAX) use multiple techniques to improve channel spectral efficiencies. In this paper we focus on one such technique, namely Coordinated Beam Switching (CBS). With CBS, each sector determines a sequence of beams (possibly with repetitions) over which it continuously cycles. Each sector independently determines its beam...
This paper proposes a sensor network framework for sensing and exploiting unknown signals. It includes distributed decision fusion, distributed processing, centralized synchronous signal sensing, centralized asynchronous signal sensing, and system of systems single sensing. Data fusion is applied to enhance the SNR of weak signals and to eliminate channel distortion. Statistical estimation and modulation...
Real time locating systems (RTLS) and wireless sensor networks are currently a hot and challenging research topic. Ultra wideband (UWB) shows promising properties for these systems, such as low-power transmitter designs and highly accurate ranging, where cm-level accuracy is achievable even in multipath intensive environments. A high-performance reference receiver architecture based on coherent processing...
Spectrum sensing is inevitable for cognitive systems to locate the spectrum holes. In the IEEE 802.22 proposal, very short quiet periods are arranged inside frames to perform a coarse intra-frame sensing whose results are then utilized to decide whether a fine inter-frame sensing is needed. The purpose of intra-frame sensing is to make an early alarm about the presence of primary users. However, the...
Time synchronization is very important to coordinate data acquisition in wireless sensor networks (WSN's). In this paper, we propose a physical-layer time synchronization scheme using ultra-wideband (UWB) signals. The synchronization is performed by emitting reference UWB signals at pairs of neighboring nodes alternatively. Once one node receive the UWB signal from the other of the pair, the local...
Wireless biomedical applications require low power operations for long, uninterrupted durations of use. In order to harness the low power characteristics of Ultra Wideband (UWB) systems, issues involving the synchronization of extremely short pulses have to be resolved as they surface as major bottlenecks of the design of such systems. The situation is particularly adverse in short range communication...
There is a general belief that in CSMACA-based wireless sensor networks (WSN) a significant number of collisions happen only because of hidden terminals. The situation when nodes start transmissions almost at the same time is considered negligible. Our experiments with motes with CC2420 radio shows that a significant number of collisions can occur even when transmitters can hear each other. The CCA...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
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