Showing papers in "Electronics Letters in 2012"
TL;DR: Simulation results in the binary-input additive white Gaussian noise channel show that the SCS algorithm has the same performance as the successive cancellation list (SCL) algorithm and can approach that of the maximum likelihood algorithm.
Abstract: A successive cancellation stack (SCS) decoding algorithm is proposed to improve the performance of polar codes. Unlike the conventional successive cancellation decoder which determines the bits successively with a local optimal strategy, the SCS algorithm stores a number of candidate partial paths in an ordered stack and tries to find the global optimal estimation by searching along the best path in the stack. Simulation results in the binary-input additive white Gaussian noise channel show that the SCS algorithm has the same performance as the successive cancellation list (SCL) algorithm and can approach that of the maximum likelihood algorithm. Moreover, the time complexity of the SCS decoder is much lower than that of the SCL and can be very close to that of the SC in the high SNR regime.
239 citations
TL;DR: In this article, an optically-pumped semiconductor disk laser providing a continuous-wave output power of 106 W at a heatsink temperature of 3°C was presented.
Abstract: A report is presented on an optically-pumped semiconductor disk laser providing a continuous-wave output power of 106 W at a heatsink temperature of 3°C. The laser, which operates in the transversal multimode regime, emits at a wavelength of 1028 nm. This high output power is achieved by carefully optimising the chip design, the growth process, and the bonding layer.
217 citations
TL;DR: In this paper, a 24 Gbit/s wireless data transmission at 300 GHz using a uni-travelling carrier photodiode (UTC-PD) emitter and Schottky barrier diode detector was designed and fabricated for larger bandwidth.
Abstract: Presented is 24 Gbit/s wireless data transmission at 300 GHz using a uni-travelling carrier photodiode (UTC-PD) emitter and Schottky barrier diode detector, which were designed and fabricated for larger bandwidth. Both the emitter and the detector were fabricated on the same epi-layer of the UTC-PD. At the link distance of around 50 cm, a bit error rate of less than 1 × 10
-10
has been achieved with the transmitted power from the UTC-PD of less than 200 μW and effective antenna gains of 40 and 35 dBi in the emitter and detector sides, respectively.
192 citations
TL;DR: In this article, an adaptive frequency and power-level tracking system is proposed for an efficient magnetic resonance wireless power transfer in the high frequency band, which is able to maintain a power transfer efficiency (PTE) of more than 75% with an optimum received power level of 88%W for any transfer distance within 0.6%m.
Abstract: To supply the optimum amount of required power to a load device, an adaptive frequency and power-level tracking system is proposed for an efficient magnetic resonance wireless power transfer in the high frequency band. As a result, the proposed system is able to maintain a power transfer efficiency (PTE) of more than 75% with an optimum received power-level of 88%W for any transfer distance within 0.6%m by directly monitoring the PTE and received power-level via wireless communication.
163 citations
TL;DR: In this article, a tri-level switching scheme for low-power successive approximation register (SAR) ADC is proposed, which reduces the number of capacitors in the ADC capacitor array by 75% and results in an area-efficient SAR ADC.
Abstract: A novel low-energy tri-level switching scheme for low-power successive approximation register (SAR) ADC is proposed. With the input common-mode voltage ( Vcm ) designed to be exactly half of the reference voltage ( Vref ), the switching energy of the proposed switching scheme is reduced by 96.89% as compared with the conventional architecture. Besides the large energy saving, the proposed switching scheme also reduces the number of capacitors in the ADC capacitor array by 75%, which in turn results in an area-efficient SAR ADC.
160 citations
TL;DR: In this article, a time-switched array (TSA) is configured to radiate radio waves which correspond to the modes associated with orbital angular momentum (OAM) theory.
Abstract: A circular time-switched array (TSA) is analysed and configured to radiate radio waves which correspond to the modes associated with orbital angular momentum (OAM) theory. Results are presented to show that the harmonic frequencies radiated by the circular TSA directly correspond to OAM modes of progressive order, including negative modes.
155 citations
TL;DR: In this paper, it was proved that the class of memristive systems encloses an elementary electronic circuit comprising a full-wave rectifier with a second-order RLC filter.
Abstract: The class of nonlinear dynamical systems known as memristive systems was defined by Chua and Kang back in 1976. Since then, many studies have addressed the search for physically-realisable memristive systems. In this reported work, it is proved that the class of memristive systems encloses an elementary electronic circuit comprising a full-wave rectifier with a second-order RLC filter.
154 citations
TL;DR: A list successive cancellation decoding algorithm to boost the performance of polar codes is proposed and simulation results of LSC decoding in the binary erasure channel and binary-input additive white Gaussian noise channel show a significant performance improvement.
Abstract: A list successive cancellation (LSC) decoding algorithm to boost the performance of polar codes is proposed. Compared with traditional successive cancellation decoding algorithms, LSC simultaneously produces at most L locally best candidates during the decoding process to reduce the chance of missing the correct codeword. The complexity of the proposed algorithm is O ( LN log N ), where N and L are the code length and the list size, respectively. Simulation results of LSC decoding in the binary erasure channel and binary-input additive white Gaussian noise channel show a significant performance improvement.
149 citations
TL;DR: A distance-constrained resource-sharing criterion (DRC) is proposed for device-to-device (D2D) communications underlaying cellular systems to mitigate the interference from cellular transmissions to the D2D link.
Abstract: A distance-constrained resource-sharing criterion (DRC) is proposed for device-to-device (D2D) communications underlaying cellular systems to mitigate the interference from cellular transmissions to the D2D link. The outage probability analysis and numerical evaluation reveal that there is an optimal minimum distance between the D2D receiver and its paired cellular UE, and the proposed DRC significantly reduces the outage probability of D2D communications.
147 citations
TL;DR: Measurements performed on the antenna after bending and integration into clothing indicate high robustness against deformation and low influence of the human body on antenna performance, making the design well-suited for on-body use.
Abstract: A novel wearable substrate integrated waveguide antenna fabricated entirely from textile materials is presented. The cavity-backed slot antenna operates in the 2.45 GHz industrial, scientific and medical band, for short range communication between rescue workers. A prototype of the antenna was fabricated and tested: good performance was obtained in terms of input matching and radiation pattern. Moreover, measurements performed on the antenna after bending and integration into clothing indicate high robustness against deformation and low influence of the human body on antenna performance, making the design well-suited for on-body use.
142 citations
TL;DR: In this article, a vertical-external-cavity surface-emitting laser (VECSEL) was used to generate femtosecond pulses at a repetition rate of 1.71 GHz.
Abstract: A quantum-well vertical-external-cavity surface-emitting laser in combination with a quantum-well SESAM is used to generate femtosecond pulses. The passively modelocked VECSEL operates at room temperature emitting an average output power of 5.1 W at 1030 nm. At a repetition rate of 1.71 GHz, the 682 fs pulses are nearly transform limited.
TL;DR: In this article, a thermoelectric generator was used for harvesting heat energy from a human body, which consisted of a polydimethylsiloxane substrate and thermoeellectric materials, and was attached to the human body for generating electrical energy.
Abstract: A report is presented on a thermoelectric generator used for harvesting heat energy from a human body. The proposed thermoelectric generator comprises a polydimethylsiloxane substrate and thermoelectric materials. The use of polydimethylsiloxane provides flexibility to the thermoelectric generator. Another advantage of using a polydimethylsiloxane substrate is that it has low thermal conductivity; this can help minimise losses in the effective heat flowing through the active thermoelectric materials. The proposed thermoelectric generator was easily fabricated using dispenser printing for thermoelectric materials. The fabricated thermoelectric generator was attached to the human body for generating electrical energy. When the temperature difference between the human body and ambient air was 19 K, the output power of the thermoelectric generator was 2.1 μW.
TL;DR: In this article, the authors proposed a positioning technique based on transmitting signals with known sinusoidal components from a number of LEDs, where the receiver uses the resultant optical signal at the receiver photodiode to calculate the receiver position.
Abstract: Energy efficient white LEDs are increasingly being used for indoor lighting but unlike conventional lighting, the intensity of the light emitted by white LEDs can be modulated at high frequencies. Described is a novel positioning technique based on transmitting signals with known sinusoidal components from a number of LEDs. The receiver uses the resultant optical signal at the receiver photodiode to calculate the receiver position. Proof of concept experiments show that white LEDs designed for indoor lighting can be used as the transmitters. The modulation bandwidth of white LEDs is large enough to give a range of localisation that is compatible with typical indoor applications.
TL;DR: In this paper, a direct intensity modulation and wireless data transmission characteristics of terahertz-oscillating resonant tunnelling diodes (RTDs) are reported.
Abstract: Direct intensity modulation and wireless data transmission characteristics of terahertz-oscillating resonant tunnelling diodes (RTDs) is reported. A direct intensity modulation of the RTD oscillators was demonstrated, and the frequency response was measured. It was found that the 3 dB cutoff modulation frequency was limited by the parasitic elements of the external circuit, and increased up to 4.5 GHz by reducing such parasitic elements. Wireless data transmission by direct amplitude shift keying was demonstrated using an RTD oscillating at 542 GHz with cutoff frequency of 1.1 GHz. The BERs for bit rates of 2 and 3 Gbit/s were found to be 2 10
-8
and 3×10
-5
, respectively.
TL;DR: In this paper, a new generation of high-speed oxide confined 850 nm vertical cavity surface-emitting laser is presented, achieving a record high modulation bandwidth of 28 GHz and error-free data transmission at bit-rates up to 44 Gbit/s.
Abstract: A new generation of high-speed oxide confined 850 nm vertical cavity surface-emitting lasers is presented. A record high modulation bandwidth of 28 GHz is achieved and error-free data transmission at bit-rates up to 44 Gbit/s is demonstrated.
TL;DR: Microelectromechanical-systems-based vertical-cavity surface-emitting lasers (MEMS-VCSELs) capable of a 150 nm continuous tuning range near 1310 nm are demonstrated and are ideal for applications such as swept source optical coherence tomography and high-speed transient spectroscopy.
Abstract: Microelectromechanical-systems-based vertical-cavity surface-emitting lasers (MEMS-VCSELs) capable of a 150 nm continuous tuning range near 1310 nm are demonstrated. These devices employ a thin optically pumped active region structure with large free-spectral range, which promotes wide and continuous tuning. To achieve VCSEL emission at 1310 nm, a wide-gain-bandwidth indium phosphide-based multiple quantum well active region is combined with a wide-bandwidth fully oxidised GaAs-based mirror through wafer bonding, with tuning enabled by a suspended dielectric top mirror. These devices are capable of being scanned over the entire tuning range at frequencies up to 500 kHz, making them ideal for applications such as swept source optical coherence tomography and high-speed transient spectroscopy.
TL;DR: In this article, a new unitary ESPRIT algorithm for joint direction of departure (DOD) and direction of arrival (DOA) estimation in bistatic MIMO radar is proposed.
Abstract: A new Unitary ESPRIT algorithm for joint direction of departure (DOD) and direction of arrival (DOA) estimation in bistatic MIMO radar is proposed. The properties of centro-Hermitian matrices are utilised to transform the complex-valued data matrix into a real-valued data matrix. Then the real-valued rotational invariance equations for signal subsapce are figured out to estimate DOAs and DODs which are paired automatically in a new way. The proposed algorithm provides increased estimation accuracy with reduced computational complexity owing to real-valued processing and double the number of data samples inherently in unitary ESPRIT. Simulation results are presented to verify the effectiveness of the proposed algorithm.
TL;DR: A triple-band CPW-fed antenna for WLAN and WiMAX applications is proposed in this article, which can obtain impedance bandwidths of 2.34-2.50, 3.07-3.82, and 5.13-5.89 GHz with reflection coefficient less than −10 dB.
Abstract: A novel triple-band CPW-fed antenna for WLAN and WiMAX applications is proposed, which can obtain impedance bandwidths of 2.34–2.50, 3.07–3.82, and 5.13–5.89 GHz with reflection coefficient less than −10 dB. The proposed antenna has a rectangular ring and an S-shaped strip attached to the feedline, with a crooked U-shaped strip and three straight strips on the bottom layer. The antenna has been successfully simulated, fabricated and measured. The measured results, which agree well with the simulated ones, show good impedance matching, nearly omnidirectional radiation patterns, and stable gains.
TL;DR: In this article, a low-complexity 8-point orthogonal approximate discrete cosine transform (DCT) is introduced. But the proposed transform requires no multiplications or bit-shift operations.
Abstract: A low-complexity 8-point orthogonal approximate discrete cosine transform (DCT) is introduced. The proposed transform requires no multiplications or bit-shift operations. The derived fast algorithm requires only 14 additions, less than any existing DCT approximation. Moreover, in several image compression scenarios, the proposed transform could outperform the well-known signed DCT, as well as state-of the-art algorithms.
TL;DR: In this article, a new record for energy-efficient oxide-confined 850-nm VCSELs with error-free performance at 25 Gbit/s was achieved with 56 ∆fJ/bit of dissipated energy per quantum of information.
Abstract: A new record for energy-efficient oxide-confined 850 nm vertical-cavity surface-emitting lasers is presented. Such VCSELs are particularly suited for optical interconnects. Error-free performance at 25 Gbit/s is achieved with 56 fJ/bit of dissipated energy per quantum of information. The influence of variations of the oxide-aperture diameter on the energy-efficiency is determined. The presented singlemode devices are more energy-efficient than similar multimode ones.
TL;DR: In this article, a new memcapacitor emulator without using any memristor is presented. But since these elements are not commercially available yet, the memristive elements emulators are very important.
Abstract: Recently, many promising applications are oriented towards the new memristive elements. But since these elements are not commercially available yet, the memristive elements emulators are very important. Introduced is a new memcapacitor emulator without using any memristor. The circuit concept and mathematical modelling are discussed analytically and numerically to validate the operation of the proposed emulator. Moreover, the proposed emulator is assembled using commercial off-the-shelf components and verified using PSpice simulations.
TL;DR: These ultra-widely tunable lasers represent the first MEMS-VCSELs reported in this wavelength range, and are ideally suited for application in ophthalmic swept-source optical coherence tomography.
Abstract: Demonstrated are 1060 nm microelectromechanical-systems-based tunable vertical-cavity surface-emitting lasers (MEMS-VCSELs) with a 100 nm continuous tuning range under repetitively scanned operation at rates beyond 500 kHz and a 90 nm continuous tuning range under static operation. These devices employ a thin strained InGaAs multiple quantum well active region integrated with a fully oxidised GaAs/AlxOy bottom mirror and a suspended dielectric top mirror. The devices are optically pumped via 850 nm light. These ultra-widely tunable lasers represent the first MEMS-VCSELs reported in this wavelength range, and are ideally suited for application in ophthalmic swept-source optical coherence tomography.
TL;DR: In this article, an adaptive method to improve the efficiency of wireless power transfer systems with axial-misalignment is presented, which achieves 48.4% relative efficiency improvement compared to a system without the proposed technique.
Abstract: Presented is an adaptive method to improve the efficiency of wireless power transfer systems with axial-misalignment. With an impedance matching circuit, the system performance increases by 11.4% with 50% misalignment at a distance of 70 cm. The proposed system achieves 48.4% relative efficiency improvement compared to a system without the proposed technique for the axial-misalignment case.
TL;DR: A new design of a compact ultra-wideband (UWB) antenna with multiple band-notched characteristic is presented and achieves an operation frequency band from 3 to 13GHz with good rejection to the Worldwide Interoperability for Microwave Access (WiMAX) and the wireless local area network (WLAN) bands in both simulated and measured results.
Abstract: A new design of a compact ultra-wideband (UWB) antenna with multiple band-notched characteristic is presented. The proposed antenna utilised a C-shape ground to realise miniaturisation and two mushroom-type electromagnetic-bandgap (EBG) structures to create notched bands. The EBG structure which comprises a slotted patch and an edge-located via can form a narrower notched band than many other structures, thus the presented design effectively saves many more useful frequencies. The antenna achieves an operation frequency band from 3 to 13GHz with good rejection to the Worldwide Interoperability for Microwave Access (WiMAX) and the wireless local area network (WLAN) bands in both simulated and measured results.
TL;DR: In this article, the realisation of a graphene FET microwave amplifier operating at 1 GHz, exhibiting a small-signal power gain of 10 dB and a noise figure of 6.4 dB, was reported.
Abstract: Reported is the realisation of a graphene FET microwave amplifier operating at 1 GHz, exhibiting a small-signal power gain of 10 dB and a noise figure of 6.4 dB. The amplifier utilises a matching inductor on the gate yielding a return loss of 20 dB. The design is optimised for maximum gain and the optimum noise figure is extracted by noise modelling and predicted to be close to 1 dB for the intrinsic graphene FET at this frequency. The presented results complement existing graphene FET applications and are promising for future graphene microwave circuits.
TL;DR: A simple TU decision algorithm is proposed that can prune a residual quadtree in the early stages based on the number of nonzero DCT coefficients and achieves a 61% reduction in TU processing time compared to the HEVC test model 3.0.
Abstract: Proposed is an early transform unit (TU) decision method for high efficiency video coding (HEVC) by early determination of the TU sizes based on coding tree pruning. Although the coding efficiency in HEVC can be improved by using various transform block sizes, the computational complexity increased dramatically in terms of the transform kernel size and the transform coding structure. A simple TU decision algorithm is proposed that can prune a residual quadtree in the early stages based on the number of nonzero DCT coefficients. Experimental results show that the proposed method achieves a 61% reduction in TU processing time compared to the HEVC test model 3.0 encoder with a little gain in coding performance.
TL;DR: In this article, a compressed sensing based approach to effectively demodulate a radar signal is discussed, and three sets of experiments are run to evaluate the demodulation performance in both simulation and real-case studies.
Abstract: The microwave Doppler radar sensor enables a non-contact approach for measuring movement in various applications. One of the most challenging issues is radar signal demodulation because it requires accurate DC offset compensation. Existing works either require a complicated setup procedure or are sensitive to environmental changes. In this reported work, a compressed sensing based approach to effectively demodulate a radar signal is discussed. Through l
1
minimisation, the proposed method can reliably demodulate noisy signals with large measurement residuals. To validate the algorithm, three sets of experiments were run to evaluate the demodulation performance. Experimental results show that the proposed method is promising in both simulation and real-case studies.
TL;DR: An optical code-division multiple access system (OCDMA) for multi-user visible light communications is presented, which interfaces with the Ethernet network, and a synchronism mechanism has been proposed and evaluated.
Abstract: An optical code-division multiple access system (OCDMA) for multi-user visible light communications is presented, which interfaces with the Ethernet network. The OCDMA scheme is based on the optical codes known as random optical codes, which do not present an optimal performance but are characterised by their ease of implementation. To combat the relative poor correlation properties of this kind of code, a synchronism mechanism has been proposed and evaluated. The results obtained with the final developed prototype demonstrate the suitability of the proposed scheme for multi-user communications in a visible light environment.
TL;DR: In this paper, a compact quad-band bandpass filter utilizing the proposed quad-mode resonator is presented, which has four tunable symmetrical resonant poles, can be treated as a two-side open-circuit stepped-impedance resonator with shortcircuit stubs in its low-IMpedance sections, and transmission zeros among each passband are generated to improve passband selectivity and achieve high isolation.
Abstract: A compact quad-band bandpass filter utilising the proposed quad-mode resonator is presented. The proposed resonator, which has four tunable symmetrical resonant poles, can be treated as a two-side open-circuit stepped-impedance resonator with short-circuit stubs in its low-impedance sections. With the multi-paths propagation mode configuration of the two resonators, transmission zeros among each passband are generated to improve passband selectivity and achieve high isolation. As an example, a quad-band bandpass filter centring at 1.9/2.8/4.3/5.2GHz is designed, fabricated and measured. The measurement results agree well with the full-wave EM simulated responses.
TL;DR: In this article, a rectenna based on a printed shorted annular ring-slot antenna with circular polarisation properties has been designed and evaluated at 2.45 GHz, where the rectifier part is localised at the back side and centred inside the radiating element.
Abstract: A compact and efficient rectenna based on a printed shorted annular ring-slot antenna with circular polarisation properties has been designed and evaluated at 2.45 GHz. The rectifier part is localised at the back side and centred inside the radiating element, resulting in a more compact structure in comparison with most conventional devices where rectifying circuit and antenna parts are geometrically clearly separated. In addition, the printed annular ring antenna is mismatched at the 4.9 GHz second and 7.35 GHz third harmonics, thus avoiding the use of an input lowpass filter. The proposed antenna and rectifier circuit have been first simulated and optimised separately using electromagnetic and circuit analyses, and then connected together. A maximum efficiency of 69% and an output DC voltage of 1.1 V have been measured over an optimised 2500 Ω resistive load at a power density of 20 µW/cm2. This rectenna is particularly suitable for powering wireless sensors or sensor networks by recycling ambient RF energy because it exhibits a global efficiency of more than 50% for power densities more than 10 µW/cm2.