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The need for secured communication between computationally weak wireless devices has driven the development of novel key generation protocols. Various schemes for extracting symmetric cryptographic keys out of wireless channel properties have been proposed during recent years, making the generation protocol more and more efficient for individual applications. However, often these schemes were evaluated...
In this study, we implemented orthogonal frequency division multiplexing (OFDM) based communication with universal serial peripheral device known USRP. We aim to study synchronization related problems of OFDM based system in real environment. The timing, phase and channel estimation are done. Their effects to the system performance are discussed. The results show that by using right tools, synchronization...
Physical layer key generation techniques based on wireless channel fading are widely considered to be secure as long as any eavesdroppers are separated from the terminals by a distance greater than the channel correlation length. This short paper discusses how this definition of the minimum secure distance is based on only a lower bound on the eavesdropper's mutual information. The non-ergodic channel...
Wireless links are typically modeled in isolation as independent and parallel links. However, in reality, there is often a correlation in defects and impairments between collocated links. The spatial correlation of shadowing among proximate wireless links has been frequently observed. Although different types of correlated shadowing models have been proposed for wireless channels, these models are...
Time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) has higher spectral efficiency than standard cyclic prefix OFDM (CP- OFDM), which is achieved by using a known pseudorandom noise (PN) sequence to replace the classical CP. However, due to the interference between the PN sequence and the data block, the performance of TDS-OFDM degrades severely over fast fading channels...
It is important to avoid secondary brain injury after Traumatic brain injury (TBI) in clinical. Cerebral perfusion pressure (CPP) is associated with blood flow into the brain, and indirectly reflects the cerebral ischemia and oxygenation. However, it is invasive and is inconvenient for continuous monitoring. Recently, near infrared spectroscopy (NIRS) has been widely applied for monitoring cerebral...
Mutual variation of the received signal which occurs as a consequence of the channel reciprocity property has recently been proposed as a viable method for secret key generation. However, this cannot be strictly maintained in practice as the property is applicable only in the absence of interference. To ensure the propagation defined key remains secret, one requirement is that there remain high degrees...
Massive MIMO has two key problems: the low-transmission efficiency caused by channel state information (CSI) feedback overhead and huge computational complexity. Authors have proposed a practical application of Massive MIMO, that is, Massive Antenna System for Wireless Entrance links (MAS-WE), and the performance of the proposed systems have been verified by computer simulations and a propagation...
The goal of this work is to establish the accuracy of ray tracing to simulate the radio channel in a Physical Layer Security scenario, where two legitimate users try to take advantage of the intrinsic properties of the channel to generate a shared secret key inaccessible to an eavesdropper. A 3D Ray-Tracing software, including a diffuse scattering model, is employed to simulate spatial correlations...
Channel randomness can be exploited to generate secret keys. However, to ensure secrecy, it is necessary that the channel response of any eavesdropping party remain sufficiently de-correlated with that of the legitimate users'. In this paper, we investigate whether such de-correlation occurs for a body area network (BAN) operating in an indoor environment at 2.45 GHz. The hypothetical BAN configuration...
In this paper, we developed a mathematical model for a single-hop relay-based communication channel. Assuming the transmitter-to-relay and receiver-to-relay channels are non-line-of-sight flat fading channels, we show that the real and imaginary components of the combined single channel have Laplace probability density functions. We, therefore, develop a complex Laplace autoregressive process (AR)...
Ultra-wideband (UWB) communication techniques are highly interesting because they seek to rearrange the huge spectrum of UWB for diverse applications. Therefore, UWB is the main technique employed in communication systems for 4G wireless networks. However, several issues in UWB technology, such as interference with various existing civil and military communication systems, require resolution. In this...
Opportunistic routing protocol is proposed for broadcast and lossy characteristics existing in wireless multi-hop networks. Compared with traditional routing protocols, opportunistic routing protocol can bring higher data transmission abilities. Traditional opportunistic routing protocols have some problems, such as too large forwarding candidates set, too high protocol calculation expense and possible...
This work is devoted to the error rate and energy-efficiency analysis of regenerative cooperative networks in the presence of multipath fading and spatial correlation. To this end, exact analytic expressions are firstly derived for the symbol-error-rate of M-ary quadrature amplitude modulation in a dual-hop decode-and-forward relay system under spatially correlated Nakagami-m fading channels and maximum...
Spectrum Sensing (SS) is one of the fundamental mechanisms required by a Cognitive Radio (CR). Among several SS techniques, cyclostationary feature detection is considered as an important technique due to its robustness against noise variance uncertainty and its capability to distinguish among different systems on the basis of their cyclostationary features. However, one of the main limitations of...
The paper presents methodology for analyzing compliance of Impulse Radio Ultra-Wideband (IR-UWB) communications systems with regulatory limits specified by US Federal Communications Commission (FCC). First, discrete spectral component that reduce Effective Isotropic Radiated Power (EIRP) in IR-UWB spectrum are analyzed in an exemplary IRUWB system. After that, a minimal Pulse Repetition Frequency...
This paper introduces mBECS(millimeter wave Band Exploration and Channel Sounder), also known as channel sounder, to explore mmWave channel characteristic. We present engineering parameters for implementation of the mmWave channel sounder to use swept time delay cross-correlation(STDCC) technique and show the measurement results of system response obtained from performance evaluation test. The dynamic...
Ellipticity statistic (EP) is a measure of multipath richness in MIMO channels that provides spatial multiplexing for their wireless systems. EP is as the ratio of the geometric mean and arithmetic mean of eigenvalues of MIMO channels. It measures the degradation of of mutual information (MI) from the ideal scenario . This work investigates the variability of EP as a function of antenna orientation...
To measure the channel variability in high-speed railway, a non-stationary metric is chosen, which is defined as the correlation of consecutive signal power samples. And the time interval is determined within which the power correlation exceeds a certain threshold. Based on this metric, the channel non-stationary characteristics of four scenarios, which are cutting, low viaduct, high viaduct and tunnel,...
The fast development of high speed railway (HSR) promotes the evolution process of wireless communication system. An accurate time delay line (TDL) channel model in HSR environments is thus necessary. In this paper, the correlation property of multi-path components based on empirical measurements at 950 MHz with 33 MHz bandwidth are characterized in real HSR propagation scenario. The results can be...
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