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Orthogonal Frequency Division Multiplexing (OFDM) is designed to improve the spectral efficiency and combat multipath fading by dividing the wide band frequency selective fading channel into many narrow flat sub-channels. The noise in the wireless communication channel may damage the OFDM transmission signal and reduce the signal-to-noise ratio (SNR) at the receiver, which limits the bit error rate...
A wireless sensor network equipped with microphones can be used for context awareness by classifying sound events in the target environment. This classification will become less accurate when more than one sound can be heard at the same time. We conduct a series of experiments in which we mix different sound types in order to see how high this influence is. We conclude, that in most cases, the classifier...
Indoor wireless transceivers connect sensors and actuators, which are carried by a mobile agent to the Smart Home Information System (SHIS). In the smart home, the sensors' role is to observe the human activities and home status, while the actuators are to perform assistive and recovery actions for serving the home resident. The SHIS then analyzes the sensors' data and issues the actuation commands...
This paper discusses the signal to noise ratio (SNR) improvement at the antenna receiver system output using non-Foster matching. High mismatch loss in an antenna reduces the external noise power below the internal noise floor which results in a lower SNR than expected appearing at the input of the receiver. Non-Foster matching can minimize the mismatch loss but also adds its own noise to the receiver...
This paper proposes a comprehensive analytical model for deriving receiver sensitivity and minimum transmit power in 802.15.6 wireless body area networks (WBANs). Formulas derived for both receiver sensitivity and minimum transmit power are determined by the signal-to-noise (SNR) ratio at the output port of the receiver, the noise floor, and the receiver noise figure. Minimum transmit power also depends...
Timely delivery of critical traffic is a major challenge in industrial applications. The Wireless Dominance (WiDOM) medium access control protocol offers a very large number of priority levels to suit time sensitive application requirements. In particular, assuming that its overhead is properly modeled, WiDOM enables an accurate evaluation of the network response time in the wireless domain, through...
The effect of wall attenuation on the uplink performance of an interference limited indoor wireless communication system is investigated. An indoor environment containing multiple co-channel access points is investigated for connections made on the basis of strongest signal or best SIR and for varying intervening wall attenuations. Power balancing is used to equalize signal-to-interference ratios...
Security is an important issue in the field of wireless channel. In this paper, the security problem of Gaussian MIMO wireless hybrid channel is considered where a transmitter with multiple antennas sends information to an intended receiver with one antenna in the presence of an eavesdropper with multiple antennas. Through utilizing some of the power to produce ‘artificial noise’, the transmitter...
Wireless communication is vulnerable to intentional electromagnetic interference, and therefore it is important to understand the interfering mechanisms. In this paper we investigate the effect of pulsed interference - as compared to continuous interference - on a receiver of digital amplitude modulated signals. To correctly receive the signals, a threshold estimate has to be computed for the proper...
Intra-electromagnetic noise coupling paths from RF-digital to RF receiver front end can be either of air, wire conduction, Si substrate or package/board. In this paper air and wire conduction coupling paths analysis is discussed. A miniature magnetic near field probe is applied to scan over the test chip to map magnetic near field at LTE band 1(2.1 GHz range). The map is reviewed to extract those...
A target can be positioned by wireless communication sensors. In practical system, the range based sensors may have biased measurements. The biases are mostly constant value, but they may jump abruptly in some special scenarios. An on-line bias change detection and estimation algorithm is presented in this paper. This algorithm can detect the jump bias based on Chi-Square Test, and then estimate the...
Impulsive noise is one of the key factor that prevents millimeter waves frequencies wireless sensors system to be fully reliable in the railway environment. Measurements of impulsive noise taken in real railway environment are required to understand the behavior of the wireless sensors under these undesired fields. In this paper, impulsive events are extracted and characterized from the measured data...
Time delay is a common phenomenon which can be varying and unknown in many networked motion control systems. Since time delay negatively affects the stability and tracking performance, it needs to be carefully handled in controller design. Moreover, both external disturbance and sensor noise exist in such systems, which makes the controller design more challenging. In this paper, a double disturbance...
In this paper, we propose a new method of secrecy signal and artificial noise (AN) transmission for a MISO wiretap channel in wireless cellular networks. We first design the secrecy signal beamformer such that its power leakage to the unintended directions is minimized, then we concentrate the AN on the directions with higher risk of information leakage, rather than broadcast it isotropically, such...
This work investigates the problem of efficient signalling for optical wireless communication systems in the presence of signal-dependent noise. We propose a novel scheme based on signalling in the square-root domain (as defined by a square-root transform) where the optical channel originally distorted by signal-dependent noise is transformed into a stationary white Gaussian noise channel. The bit...
Recently, it has been shown that the electromagnetic interference generated by computer platforms like laptops, smart phones, tablets, or PDAs fits a double-sided K-distribution statistic. This kind of impulsive noise can severely degrade the performance of linear receivers intended for operation under additive gaussian noise. Therefore, we propose the use of a quasi-optimal detection scheme with...
With the rapid spread of the light emitting diode (LED), visible light communication (VLC) is becoming an emerging wireless communication technology. VLC offers advantageous properties such as safety, environmental protection, worldwide availability and high capacity. It can be used as an effective supplement of the existing wireless communication. Power line communication (PLC) using the omnipresent...
The problem of transmitting confidential messages in the M × K wireless X network is considered, in which each transmitter intends to send one confidential message to every receiver. In particular, the secrecy degrees of freedom (SDOF) of the considered network are studied by an artificial noise alignment (ANA) approach, which integrates interference alignment and artificial noise transmission. At...
This paper presents a 12-channel, low-power, high efficiency neural signal acquisition front-end for local field potential and action potential signals recording. The proposed neural front-end integrates low noise instrumentation amplifiers, low-power filter stages with configurable gain and cut-off frequencies, a successive approximation register (SAR) ADC, and a realtime compressed sensing processing...
Horizontal spectrum sharing occurs when multiple users share a given band of frequencies with no central control or coordination, and all users compete for access to the available spectrum. Depending on the actual approach used to allocate transmit power over available channels, mutual interference may affect user performance. Three types of horizontal spectrum sharing scenarios will be outlined in...
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