A remotely-powered, 20 Mb/s, 5.35 pJ/bit impulse-UWB WSN tag for cm-accurate-localization sensor networks

This paper presents an ultra-low-power, low-voltage sensor node for wireless sensor networks. The node scavenges RF energy out of the environment, resulting in a limited available power budget and causing an unstable supply voltage. Hence, accurate and extensive power management is needed to achieve proper functionality. The fully integrated, autonomous system is described, including the scavenging circuitry with integrated antenna, the power detection and power control circuits, the on-chip clock reference, the UWB transmitter and the digital control circuitry. The wireless sensor node is implemented in \(0.13 \,\upmu \hbox {m}\) CMOS technology. The only external components are a storage capacitor and a UWB transmit antenna. The system consumes only \(113\, \upmu \hbox {W}\) during burst mode, while only 8 nW is consumed during the scavenging operation, enabling an efficiency of 5.35 pJ/bit which is significantly better than current state-of-the-art UWB tags. Due to the use of impulse-radio UWB, also cm-accurate localization of the tag can be achieved.     

1D dielectric electromagnetic band gap (EBG) resonator antenna design

This article presents a new methodology allowing to design a planar electromagnetic band-pap antenna (choice of theebg material, sizing, feeding). This kind of antenna has already been presented.ebg antennas are very thin (compared with parabolic reflectors) high gain antennas. This article makes easier the realization ofebg antennas whatever the operating frequency, the gain, or still the bandwidth. A study about the sensitivity of the material properties on the performances is also presented. Finaly two exemples using this design method are described.     

A 3–10 GHz Ultra Wideband Receiver LNA in 0.13 \mu m CMOS

A fully integrated low-power, low-complexity ultra wideband (UWB) 3–10 GHz receiver front-end in standard 130 nm CMOS technology is proposed for UWB radar sensing applications. The receiver front-end consists of a full UWB band low-noise amplifier and an on-chip diplexer. The on-chip diplexer has a 1 dB insertion loss and provides a \(-\) 30 dB isolation. The diplexer switch was co-designed with the receiver input matching network to optimize the power matching while simultaneously achieving good noise matching performance. The receiver low-noise amplifier provides a 3–10 GHz bandwidth input matching and a power gain of 17 dB. The overall receiver front-end consumes an average power of 13 mW. The core area of the transceiver circuit is 500 \(\mu \) m by 700 \(\mu \) m.     

Simple iterative receivers for MIMO LP-OFDM systems

In this paper,Lp-ofdm is combined with differentMimo schemes in order to improve performance in terms of diversity gain and to exploit capacity brought by theMimo channel. The original contribution is the development of a generic iterative receiver designed forLp mimo transmission able to work whatever the antenna configuration and the spatial coding scheme. By using a globalMmse criterion, interference terms coming from space-time coding and linear precoding are jointly treated leading to a very good trade-off between performance and complexity compared to trellis based detectors particularly for high order modulations, high number of antennas and/or large size of precoding matrices.     

Compact Coplanar Waveguide-fed Planar Antenna for Ultra-wideband and WLAN Applications

A novel compact planar antenna is presented for Ultra-wideband (UWB) applications in this paper. The proposed antenna has rectangle-like slot and it is fed by coplanar waveguide. The antenna is printed on FR4 substrate and it has compact size of $28 \times 31 \times 0.8 \,\,\text{ mm}^{3}$ . Parametric study is performed on the antenna by investigating the effect of various geometrical parameters on the frequency characteristics. The antenna is fabricated and measured. It has better return loss response and stable gain over the entire UWB band. The antenna has stable radiation pattern and good impedance matching over entire ultra-wide bandwidth of 3–10.6 GHz. The results show that there is good agreement between measured and simulated results. Various features such as compactness, simple configuration and low fabrication cost make the antenna suitable for UWB and wireless local area network systems.     

A Statistical Model for the Influence of Body Dynamics on the Gain Pattern of Wearable Antennas in Off-Body Radio Channels

The goal of this paper is to address a statistical approach for modelling the influence of body dynamics on the gain pattern of wearable antennas in Body Area Networks, particularly in off-body radio channels. A dynamic model was developed based on Motion Capture data, describing a realistic human body movement. Antennas are located on 4 typical positions (i.e., Head, Chest, Arm and Leg), for which statistics of antenna orientation (i.e., average and standard deviation of elevation and azimuth angles) were calculated for 2 dynamic scenarios, i.e., Walk and Run. Based on the rotation of the antenna, the statistics of gain patterns of a wearable patch antenna operating at 2.45 GHz were calculated. The standard deviation of the change in the antenna orientation is the highest for the Arm location, reaching $19^{\circ }$ and $37^{\circ }$ for the Run scenario, for elevation and azimuth angles, respectively. For most of the scenarios, the distribution of the change in antenna orientation fits well to a Kumaraswamy distribution (using the $\chi ^2_{95\,\%}$ test). For all antenna positions and the Walk scenario, the standard deviation is $<4^{\circ }$ .     

Downlink SINR Study in Multiuser Large Scale Antenna Systems

In this paper, the downlink signal-to-interference-plus-noise ratio (SINR) performance in multiuser large scale antenna systems with matched filter (MF) and regularized zero-forcing (RZF) precoding is investigated. The probability density function (PDF) for MF is derived and the distribution in high signal-to-noise ratio (SNR) regime is studied. Results indicate that the PDF of downlink SINR for MF converges to \(\mathcal F\) distribution when the interference is dominant over noise. For MF, the asymptotic SINR is just the reciprocal of the ratio of the number of users \(U\) to the number of transmit antennas \(N\) , and is irrelevant to the average transmit power when \(N\) and \(U\) grow with fixed ratio. However, when \(U\) is a large constant, the transmit power could be proportional to \(\ln N \big /N \) to maintain a specified quality of service, as a result of the large scale antenna system effect. In addition, the closed form of asymptotic SINR for RZF is derived by solving two mathematical expectations related to eigenvalues of large dimensional random matrices. Simulation results validate the derived PDF and analytical results.     

FDTD simulations and measurements for cell phone with planar antennas

The Finite-Difference Time-Domain (fdtd) method is used to calculate the cellular phone far and near field and the specific absorption rate (sar) in the user’s head. The conventional λ/4 monopole and a simple planar antenna are simulated and measured. The simulated results are in good agreement with those measured for thevswr and for the radiation patterns on the horizontal and vertical planes. These results show that significant improvements in the antenna radiation efficiency and in the reduction of thesar in the head are obtained when planar antennas are used.     

Compact Planar Monopole Antenna with Dual Band Notched Characteristics Using T-Shaped Stub and Rectangular Mushroom Type Electromagnetic Band Gap Structure for UWB and Bluetooth Applications

In this paper, an ultra-wideband (UWB) antenna with dual band-notched characteristics is proposed. The proposed antenna also covers ISM (Industrial, Scientific, and Medical)/Bluetooth band. The antenna consists of a microstrip fed truncated U-shaped patch, T-shaped stub, rectangular mushroom type electromagnetic band gap structures (EBG), and partial ground plane. To mitigate the problem of interference due to standard narrow bands (like wireless interoperability microwave access (WiMAX) and wireless local area network (WLAN)) lie in the range of UWB, dual band notched characteristics is introduced. The WiMAX and WLAN band notched characteristics are realized by introducing a T-shaped stub and rectangular mushroom type EBG structures, respectively. The proposed antenna is printed on a 1.6 mm thick FR4 substrate with relative permittivity \((\upvarepsilon _{\mathrm{r}})\) 4.4 and the size of actual antenna is \(36 \times 40\hbox { mm}^{2}\) . The measured results shows that the proposed antenna attains a wide impedance bandwidth \((\hbox {VSWR} \le 2)\) from 2.35 to 11.6 GHz with dual band notched characteristics from 3.29 to 3.9 GHz and 5.1 to 5.85 GHz with stable radiation patterns. The time domain behaviors of the proposed antenna is also analyzed for pulse handling capability.     

Design of an Ultra-Wideband Microstrip Patch Antenna Suspended by Shorting Pins

Designing a compact wideband microstrip patch antenna which is composed of a folded-patch feed, a symmetric E-shaped edge and shorting pins is presented in this paper. One pin is applied in order to expand the impedance bandwidth. Two other pins are utilized to miniaturize the size of patch as well. The measured impedance bandwidth ( $\text{ VSWR}\le 2$ ) of the fabricated antenna is more than 90 % in the frequency range 3.92–10.67 GHz for ultra-wideband (UWB) applications. The antenna size is $0.438\lambda _{0}\times 0.365\lambda _{0}\times 0.170\lambda _{0}$ at its center operating frequency. Also, radiation patterns with acceptable stability within the bandwidth are obtained. In addition, the effects of some key parameters are investigated to describe the performance of the proposed design.     

BER Evaluation of IEEE 802.15.4 Compliant Wireless Sensor Networks Under Various Fading Channels

This paper presents bit error rate (BER) analysis of wireless sensor networks (WSNs) consisting of sensor nodes based on an IEEE 802.15.4 RF transceiver. Closed-form expressions for BER are obtained for WSNs operating over AWGN, Rayleigh and Nakagami-m fading channels. For the purpose of analysis, we consider an IEEE 802.15.4 RF transceiver using direct sequence spread spectrum-offset quadrature phase shift keying (DSSS-OQPSK) modulation under 2.4 GHz frequency band in a WSN. Analytical expressions for BER are derived for a wireless link between sensor nodes that act as a transmitter unit and a base station without considering the effect of interferers in the wireless environment. Numerical results for BER are obtained by varying the IEEE 802.15.4 standard specific physical layer parameters, such as number of bits used to represent a Zigbee symbol, number of modulation levels used in an OQPSK modulator, and various values of Rayleigh and Nakagami-m fading parameters, denoted as \(\alpha \) and \(m\) , respectively. Moreover, optimum values of physical layer parameters are identified for improved system performance. It is found that error performance analysis of WSN shows improvement when lower number of bits is used to represent a Zigbee symbol. Specifically, under a Rayleigh fading channel which reflects a real-time WSN environment, the network exhibits better performance only when it is operated at high SNR values, i.e., BER of order \(10^{-2}\) is achieved when SNR lies in the range 5–15 dB. Also, the effect of fading parameters on network performance shows that better results are obtained for higher values of \(\alpha \) and \(m\) for Rayleigh and Nakagami-m fading channels, respectively.     

Robust time-frequency distributions based on the robust short time fourier transform

Design of time-frequency distributions (Tfds) that are robust to the impulse noise influence is considered. The robustTfds based on the robust short-time Fourier transform (Stft) are proposed. An efficient procedure to evaluate the robustStft is given. RobustTfds based on the robustStft have better energy concentration around the signal instantaneous frequency (If) than the robustStft itself. Also, theseTfds are more resistant to higher impulse noise than the robustTfds obtained using the local autocorrelation function (Laf) based minimization problem.     

Miniaturized Trapezoidal Patch Antenna with Folded Ramp-Shaped Feed for Ultra-Wideband Applications

A novel design for compact probe-fed wideband microstrip patch antenna for ultra-wideband (UWB) applications is proposed in this paper. The antenna consists of a folded ramp-shaped feed, trapezoidal patch and shorting pins. By adding two pins at end side of the patch, its size is miniaturized. The measured impedance bandwidth (VSWR  $\le $  2) of fabricated antenna is more than 130 % from 3.7 to 17.6 GHz. This antenna achieves an acceptable miniaturization and provides an excellent UWB impedance bandwidth with stable radiation patterns. It is shown by simulated results how the bandwidth can be considerably increased by introducing novel feeding method namely, the folded ramp-shaped feed. Likewise, the parametric study is performed to describe the characteristics of the proposed antenna. Moreover, good antenna performances such as radiation patterns, acceptable miniaturization and antenna gains over the operating band have been observed.     

Electronically scanned RF-to-bits beam aperture arrays using 2-D IIR spatially bandpass digital filters

A beamforming system based on two-dimensional (2-D) spatially bandpass infinite impulse response (IIR) plane wave filtering is presented in a multi-dimensional signal processing perspective and the implementation details are discussed. Real-time implementation of such beamforming systems requires modeling of computational electromagnetics for the antennas, radio frequency (RF) analog design aspects for low-noise amplifiers (LNAs), mixed-signal aspects for signal quantization and sampling and finally, digital architectures for the spatially bandpass plane wave filters proposed in Joshi et al. (IEEE Trans Very Large Scale Integr Syst 20(12):2241–2254, 2012). Multi-dimensional spatio-temporal spectral properties of down-converted RF plane wave signals are reviewed and derivation of the spatially bandpass filter transfer function is presented. An example of a wideband antipodal Vivaldi antenna is simulated at 1 GHz. Potential RF receiver chains are identified including a design of a tunable combline microstrip bandpass filter with tuning range 0.8–1.1 GHz. The 1st-order sensitivity analysis of the beam filter 2-D $\mathbf z $ -domain transfer function shows that for a 12-bits of fixed-point precision, the maximum percentage error in the 2-D magnitude frequency response due to quantization is as low as $0.3\,\%$ . Monte-Carlo simulations are used to study the effect of quantization on the bit error rate (BER) performance of the beamforming system. 5-bit analog to digital converter (ADC) precision with 8-bit internal arithmetic precision provides a gain of approximately 16 dB for a BER of $10^{-3}$ with respect to the no beamforming case. ASIC Synthesis results of the beam filter in 45 nm CMOS verifies a real time operating frequency of 429 MHz.     

Source primaire multi-éléments et matrice de commutation associée pour satellite de télécommunication utilisé en mode AMRT

This paper describes a 12 GHz primary feed system designed for a scanning spot-beam transmitting antenna system operated in time-division multiple access (tdma) mode. The feed is made of three main parts: a radiating cluster consisting of seven horn elements, apin diode switch device which performs electronic scanning of the beam by successively activating the seven radiating elements, arf sensing waveguide network. The antenna system features are designed to optimize the gain throughout the coverage. A minimum directivity above 46 dB (without considering power losses due to the switch device) in a 1.35° coverage (corresponding to France) is expected from measured characteristics of the primary feed. This is corresponding at a 4 to 5 dB improvement upon a global beam system.     

Uplink Sum-Rate Analysis of Massive MIMO System with Pilot Contamination and CSI Delay

We consider multi-cell multi-user massive MIMO system under correlated Rayleigh fading channels. Taking pilot contamination and CSI delay into consideration, we derive the equivalent channel model with MMSE channel estimation and one-tap prediction. Employing this equivalent channel model, the lower bound of the uplink sum-rate is derived, and its asymptotical performance is studied when the base station antenna number goes without bound. We find that if we schedule the \(k\) -th user of all cells who have the same prediction coefficient, the uplink sum-rate is the same as the one with no CSI delay when the number of BS antennas goes without bound at a much greater rate than the number of users. Simulation results show that the asymptotic approximation has good performance for large \(M\) , and suggest that large antenna array can compensate for the decay due to CSI delay. Simulation results also verify our guess that CSI delay does not necessarilly decrease the uplink sum-rate due to the impact of pilot contamination.     

A MC-CDMA system analysis in a software radio context

This paper presents a Multi-Carrier Code Division Multiple Access (Mc-Cdma) system analysis in a software radio context. Based on a combination of multi-carrier modulation and code division multiple access,Mc-Cdma benefits from the main advantages from both schemes: high spectral efficiency, high flexibility, multiple access capabilities, etc. It is firstly shown why, nowadays,Mc-Cdma is undoubtedly a high potential candidate for the air interface of the 4G cellular networks. TheMc-Cdma concept and the block-diagrams of the transmitter and the receiver are presented first. Afterwards, the technical issues concerning the processing devices for the implementation ofMc-Cdma systems in a software radio context are analysed. The advantages and disadvantages of Digital Signal Processors (Dsps) and Field Programmable Gate Arrays (Fgpas) components are discussed. The implementation ofMc-Cdma systems and the integration of signal processing algorithms as Fast Hadamard Transform (Fht) and Inverse Fast Fourier Transform (Ifft) are considered and analysed for the first time. Finally, implementation results with a mixed prototyping board are presented. Then, it is shown that a new combination of the flow graphs ofFht andIfft leads to interesting computation savings and that hardware structures asFgpas are more adapted thanDsps to those intensive computation functions. Finally, for the completeMc-Cdma modem implementation, the necessity of a Co-Design methodology is highlighted in order to obtain the best matching between algorithms and architecture.     

An Equivalent Circuit Model for Broadband Modified Rectangular Microstrip-Fed Monopole Antenna

A new, simple equivalent circuit model for designing a multi-mode/broadband modified rectangular microstrip-fed monopole antennas using stepped cut at four corners (SCFC) method has been presented in this paper. The SCFC method is a method in which the four corners at the edges of the patch are cut for the purpose of designing the microstrip-fed monopole antenna. The design procedure of a single mode to a broadband microstrip-fed monopole antenna is explained in order to help understand more about the proposed equivalent circuit model and SCFC method. The computer simulation technology (CST) microwave studio and advanced design system (ADS) software are used to design and simulate of the proposed microstrip-fed monopole antennas and their equivalent circuit model, respectively. The operating bandwidth of the broadband antenna with \(\hbox {S}_{11}< -10\) dB, covers the operating frequency range from 0.9 to 2.6 GHZ that it is suitable for GSM (0.9 GHz), WiFi (2.4 GHz) and LTE (2.6 GHz) applications. For the purpose of validating the simulated results, the antennas prototype has been fabricated and measured. The comparison of the measurement and simulation results shows that, there is a good agreement between them.     

Mitigation of Antenna Displacement with Array Antenna for Data Transmission in Wireless Power Transfer System

Magnetic resonance wireless power transfer is expected to be one of the prevalent schemes because of its high efficiency and long transmission range. However, in this scheme, there is a problem that the characteristics of a transmission channel changes in according with the distance between coil antennas. This paper investigates the performance of data transmission with an array antenna in a wireless power transfer system. In the assumed system, the same antennas for wireless power transfer are used for data transmission. The assumed system uses multiple transmit antennas and beamforming is realized by shifting the phases of signals in a transmitter. Numerical results obtained through computer simulation show that the proposed scheme can mitigate the dependently of a bit error rate (BER) to the distance between the antenna coils. The variation of the performance is suppressed within 1–3 dB at the BER of \(10^{-5}\) in the case of two transmit antennas. In addition, the system with two transmit antennas achieves 2 dB or more improvement in term of the BER performance than that with a single antenna at specific antenna distances.