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The wireless channel behaves markedly different depending on whether a line-of-sight (LOS) between transmitter and receiver exists or not. State-of-the-art wireless channel models for mobile communications, such as, IST WINNER-II and the 3GPP 3D channel model specified in TR 36.873, define distinct macro- and microscopic fading parameters for LOS and non-LOS (NLOS) situations. Whether a user is in...
In cache-aided networks, due to the multicast nature of wireless signals, coded multicast delivery results in significant load reductions that are proportional to the aggregate cache size. State of the art caching schemes exploit exact content reuse across the network, which, due to the personalized nature of the content consumed by users, can lead to limited efficiency of the scheme. In this work,...
The main goal of this paper is to explain the definition of the term Time-Reversal in Electrical engineering in general, and in electromagnetics for wireless communications to be specific. First, the goal will be to illustrate its claimed capabilities. Some problems with the application of time reversal in electromagnetics will be discussed both theoretically and practically. All of the time reversal...
Internet of Things (IoT) is founded on the unprecedented proliferation of heterogeneous wireless technologies. However, dense deployment of such devices intensify the interference, which has become a major cause of performance degradation. This paper first introduces schemes for harmonious coexistence. Our designs effectively enhance diverse existing protocols via a complementing middle layer that...
This paper concerns on inefficiency or even failure in secret key generation caused by the imperfect channel state information. We propose a secret key generation scheme based on wavelet analysis. Firstly, the channel estimates are pre-processed by wavelet analysis to improve the correlation. Secondly, to ensure the randomness of the secret keys, an adaptive equal probability quantization approach...
UWB based on chirp waveforms has the advantages of low cost, low power consumption and high processing gain. A multiple access UWB system based on multi-chirp waveforms is proposed[ Sponsored by Tianjin science and technology planning project(No:13ZCZDSY20100)], which enables the system to gain merits of both IR-UWB and OFDM-UWB. System performance for multi-user UWB using multi-chirp waveforms is...
Key generation from wireless channels is a promising alternative to public key cryptography for the establishment of cryptographic keys. It is the first paper to experimentally study the channel reciprocity principle of key generation, through investigating and quantifying channel measurements' cross-correlation relationship affected by noise and non-simultaneous measurements. Channel measurements,...
This paper proposes a simple formulation for computing the full cross-covariance of multi-user multi-antenna multipath propagation channels where the multipath characteristics observed at two adjacent radios are correlated. The technique is applied to the case of key establishment based on reciprocal electromagnetic propagation to demonstrate the impact of a proximate eavesdropper on the key rate...
The performance of a multiple-input-multiple-output (MIMO) system employing circularly polarized (CP) antennas are addressed in the case of indoor propagations. In particular, the comparison between a MIMO system employing CP antennas with respect to linearly polarized (LP) ones has been carefully investigated. To this purpose a set of antennas operating in CP or LP has been designed to operate at...
Wireless Body Area Networks is a research field expanding quickly due to increased global demand for body worn electronics. In some cases measurements taken by these devices may seem odd, due to the unknown context in which they are taken. Localisation is a step towards greater context awareness about devices being worn, and an alternate solution to localisation using inertial measurements is used...
Human daily activity recognition using mobile personal sensing technology plays a central role in the field of pervasive healthcare. One major challenge lies in the inherent complexity of human body movements and the ECG signals. To tackle this problem, in this paper, we present a human activity recognition and ECG based on SHIMMERTM Wireless sensor platform. We are developing ubiquitous system for...
Since its advent, the wavelet filtering technique provides time-diversity gains to M-ary digital communications systems, while it keeps their spectral efficiency unaffected. However, the receiver design is more critical under this novel time-diversity transmission system. To tackle this problem, we propose a MMSE-based receiver. This paper presents the performance evaluation of a novel wavelet-filtered...
Spoofing that emulates authentic signals to coerce target receivers into false navigation solutions is a severe threat to many applications based on Global Positioning System (GPS). In order to forge a reasonable navigation solution, a spoofer generally has to mimic signals of several GPS satellites simultaneously. In view of the fact that GPS signals originated from a single transmitter would essentially...
In relay wireless systems, a data packet transmitted by a source node is forwarded by one or many relays nodes before reaching the destination node. In actual technologies, the destination recovers the identities of the sources and relays of received signals by using signaling information exchange before the data exchange and by including identities information (addresses) in data sequences. In this...
The concurrent deployment of heterogeneous wireless networks such as Wi-Fi, Bluetooth, and ZigBee has led to the severe interference problems in the 2.4GHz ISM band. In particular, ZigBee networks are susceptible to the interferences from other wireless technologies; For example, strong Wi-Fi signals trigger false alarms to ZigBee device that is performing low power idle listening and cause appreciable...
This paper explores fundamental properties of wireless communication using polarization-based modulation. Channel models for polarization shift keying (PolSK) are developed assuming additive white Gaussian noise (AWGN) and Rayleigh fading; the resulting analysis of a maximum likelihood receiver yields a bound on the symbol error rate (SER) for PolSK that is approximately 1.0 dB tighter than the previously...
For M-ary spread spectrum (MSS) communication systems with orthogonal frequency division multiplexing (OFDM) technique, a simple scheme to generate lots of MSS sequences is presented on the basis of circular shift and selection operation. The number of the generated sequences is far larger than sequence length at the cost of the decreased correlation property, which is significantly important to improve...
Time-varying channel estimation is a well-known challenge for wireless communications on high-speed railways. Existing estimation algorithms include interpolation, basis expansion model (BEM) and autoregressive models. These methods remain unchanged for every scenario on high speed railways (HSRs), such as viaducts, tunnels, cutting and open areas. Thus their estimation performance are not consistent...
In this paper, we compare the statistical properties of high-speed train (HST) wireless channels in different scenarios using a generic non-stationary HST channel model that has been verified by channel measurements [1]. We mainly focus our comparison and analysis on the three most common HST scenarios, i.e., the rural area, cutting, and viaduct scenarios. Several channel statistical properties such...
Two methods to estimate the direct current offset (DCO) of non-coherent receivers for on-off keying (OOK) systems are proposed. These estimate I-arm and Q-arm DCO solely from the digitized samples of the envelope detector. This ameliorates power consuming individual I-arm and Q-arm processing for DCO estimation and makes it more suitable for adoption in next generation wireless ultra-low power (ULP)...
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