An experimental bistatic X-band continuous-wave life-detection radar is proposed. The system operates with two directive high gain antennas and a programmable transmitter and receiver. A method based on the independent component analysis, and accurate breath and heartbeat movements models are applied to suppress the interference and to better identify the respiratory and heart movements. The obtained experimental results show that this system can effectively detect the heartbeat and the respiratory activity with a good accuracy and demonstrated the capabilities and the potentialities of such system.

A new formulation for the latency insertion method (LIM) by implicitly substituting the voltages in the currents is presented. LIM is a fast transient analysis technique for large networks. However, due to its explicit formulation, it has a limitation on the time step size to guarantee numerical stability, similar to the finite-difference time-domain technique. This limits the efficiency of the method particularly where small parasitic inductances and capacitances are present which necessitates the use of very small time steps. Using the new formulation, an improved LIM is presented, where accurate and stable results can be obtained without limitation on the time step size.

The data rate of a Tomlinson–Harashima (TH) precoder is limited by the delay in the feedback path of its infinite impulse response (IIR) filter that cancels the channel's post-cursor intersymbol interference (ISI). One reason for long loop delays is the requirement to perform the ISI subtraction from the data signal in binary arithmetic in order to properly execute the modulo (MOD) operation, which stabilises the IIR filter and limits the transmitter amplitude. The restriction to binary arithmetic is unfortunate, because some filter subcomponents such as, e.g. adder trees are often implemented in a faster data format that has no slow carry propagation [e.g. the carry-save adder (CSA) format]. This paper proposes a novel architecture for TH precoders in which the MOD operation is taken out of the loop, so that the remaining IIR filtering is performed entirely in CSA arithmetic to reduce the feedback delay as no conversion to binary format is required within the loop. With the pipelining technique applied, the filter's feedback delay reduces to the propagation delay of a multiply-accumulate unit operated with CSA arithmetic. The proposed concept was verified in a 14 nm CMOS test chip with multi-level signalling (NRZ, 4-/8-/16-PAM).

An improved bang-bang phase detector (PD) for multi Gb/s clock and data recovery (CDR) circuits is presented. The proposed PD is based on inverting the Alexander PD. In a typical subsampled CDR circuit, this Inverse Alexander PD results in a ten times better bit error rate (BER) compared with the conventional Alexander PD. Additionally, in the case of duty-cycle distorted input data, this Inverse Alexander PD can even reach 20 times better BER compared with the conventional Alexander PD.

Designs that operate at sub-threshold voltages are a promising response to the ultra-low power demands of many modern applications with relaxed performance requirements. Towards this approach, a pass-transistor-logic-based programmable delay line (DL) circuit is presented that is designed specifically for sub-threshold operation. Compared with the commonly used design, the DL consumes 79.2% less dynamic energy, 83.5% less leakage power, 47.2% better linearity across codewords, 58.6% smaller active area, and with similar resiliency to variations across Monte Carlo simulations.

A novel image descriptor for fingerprint liveness detection is presented. Inspired by the observation that textural distortions due to the fabrication process are well revealed by edge-aware filtering, it is proposed to exploit the local patterns on the accumulated smoothing space for determining whether a given fingerprint is fake or not. Experimental results on LivDet 2009 and 2011 datasets show the efficiency and robustness of the proposed method compared with previous local image descriptors.

A novel and efficient method for person re-identification based on orthogonal dictionary learning is proposed. The orthogonal dictionary exhibits extraordinary discriminative power than the classical dictionary learning. It is learned with the help of convex optimisation and customised trace optimisation. The approach has been evaluated against current methods on a benchmark dataset and can reach outstanding performance.

Mendelsohn design was first used to construct n − 1 blocks of one optimal 2−(n, n, 2) packing which is isomorphic to an (n, n − 1, n − 1) permutation array. The n-ary shift register (SR) formed by a group of k binary SRs of length n was constructed and then used to operate n − 1 blocks of the 2−(n, n, 2) packing which can generate n(n − 1) blocks of another optimal 2−(n, n, 2n) packing from which a family of (n, n(n − 1), n − 1) permutation codes can be constructed.

Modifying flow rule attack posts a huge threat to controllers in network operating system (NOS) for software defined network (SDN) due to its concealment. Based on the previously proposed NOS architecture with multiple controllers which introduce heterogeneity and dynamic to defend above attack effectively, its dynamic segment about dynamically scheduling controllers is explicitly presented. A dynamic-scheduling method is put forward to maximise security gain of NOS during each switch. This algorithm is able to improve NOS security through altering its framework's diversity to maximum degree while considering switching cost and latency simultaneously. Theory analysis and simulation results prove validity and availability of the devised mechanism and its more effective security performance over traditional architectures.

A spur reduction technique in fractional-N phase-locked loops based on a current-mode phase interpolator (CMPI) is presented by dithering input signals of the CMPI. CMPI shows deterministic phase error having symmetrical profile around 45° offset in each quadrant, and this non-linear property leads to fractional spurs. The proposed 45° phase rotator with digital compensation reduces the fractional spur by 18.57 dB at most, and average improvement of fractional tones is 7.89 dB in 2 MHz frequency step measurement.

In many applications, an incoming value is compared against one or more values stored in registers. To avoid data corruption, the registers are in some cases protected with a single error correction (SEC) code. Therefore, in a traditional implementation, SEC decoding would be done before the comparison. However, previous works have shown that it may be more efficient to compare the SEC encoded values directly using a distance one comparison. This distance one comparison prevents single bit errors from affecting the result of the comparison and is in many cases simpler than an SEC decoding plus a traditional comparison. It is shown that the use of single-error correction double error detection (SEC-DED) encoded registers enables a simplified distance one comparison that can further reduce the cost of implementing error protection for register comparison.

Constrained interleaved coded modulation technique known to map coded bits of outer block codes onto a higher-order constellation is extended with suitable adjustments for outer convolutional codes. A novel puncturing technique based on the mapping is proposed to generate powerful punctured coded schemes. It is demonstrated that the proposed mapping and puncturing techniques are significantly better than their traditional counterparts.

A joint cooperative jamming and opportunistic scheduling (CJOS) scheme is proposed for a downlink multiuser relay network (MRN) with an untrusted fixed-gain amplify-and-forward relay. Specifically, the source's confident message is protected by employing CJ at the destinations and multiuser diversity is harvested via OS. Unified tight approximation and asymptotic expressions for the system secrecy outage probability with perfect/outdated channel state information (CSI) are derived. Our results explicitly show that with perfect CSI, CJOS scheme can improve the secrecy diversity order from 1/2 in single-user networks up to full diversity of 1 in MRNs. However, the outdated CSI degrades the secrecy diversity order from 1 to 1/2.

A combinational biasing technique is presented for a 400–450 MHz power amplifier (PA). By combining two class AB amplifiers with different conduction angles and optimising the design parameters as well, the 5th and 6th harmonics are greatly suppressed in the PA's output. The designed PA is fabricated in 65 nm CMOS technology. Measurement results show that with the presented technique the 5th and 6th harmonic suppressions can be improved by 13 and 17 dB, respectively, compared with a PA with a fixed conduction angle. The presented PA technique can find its important use in multi-protocol transceivers.

A miniaturised spherical resonator based X-band dual-mode bandpass filter that is 3D printed using a ceramic filled photosensitive resin is the first time presented. This filter has substantially enhanced thermal handling capability than its counterparts that are printed out of the conventional resins with a relatively low working temperature. The filter's thermal handling capability is experimentally characterised by measuring its RF performance under different working temperatures using a pair of tailor made aluminium thermal isolators to separate the network analyser from the heat source. The measured results demonstrate that the ceramic resin based filter is capable of operating at much higher temperatures, and has a much better thermal stability than the one made of ordinary resin, without losing its intrinsic light-weight advantage over the one made of metal. This type of thermally-stable ceramic filled resin can be widely applied to stereolithography-based 3D printed lightweight microwave and millimetre-wave waveguide devices.

A novel compact microstrip lowpass filter with high performance is designed and analysed based on transfer function. The main resonator consists of L-shaped and T-shaped patches. The L-shaped resonator is used to increase the width of the stopband. The presented filter has −3 dB cut-off frequency at 2 GHz. It also has a wide stopband about 17.82 GHz with the suppression level of −21 dB. The transition band is ∼168 MHz from −3 to −40 dB. The locations of transmission zeros are calculated by transfer function. The presented lowpass filter has other advantages, such as high return loss more than 20 dB and low insertion loss <0.15 dB in the passband. The size of the filter is only 0.087 × 0.170 λ_g ², where λ _g is the guided wavelength at the cut-off frequency. The proposed lowpass filter has the figure of merit of 50,285, which shows its strong efficiency. The lowpass filter is simulated and fabricated and there is a good agreement between the simulation and measurement results.

Through-wall imaging (TWI) is a challenging topic in the area of inverse scattering problem based microwave imaging. A TWI solution based on non-linear inversion algorithms is experimentally investigated. Experiments are performed using a setup with the object surrounded by a closed wall. The inversion is based on a twofold subspace-based optimisation method, and the results show that the location, shape, size, and dielectric constant of the object can be successfully retrieved from the measured scattering data. This is the first experimental demonstration of TWI of objects behind a closed wall using a non-linear inversion algorithm. These results imply the potential of TWI for practical applications.

The channel temperature rise is demonstrated due to self-heating in narrow tri-gate fully depleted silicon-on-insulator devices becomes inaccurate when extracted using the gate resistance thermometry. Thermal resistance and channel temperature have been extracted by both gate resistance measurements and 3D TCAD electrothermal simulations for tri-gate wide and nanowire MOSFETs down to 12.5 nm fin width. A critical fin width around 500 nm the extracted channel temperature accessed by the gate resistance thermometry differs significantly from the actual channel temperature due to heat dissipation through the gate contacts is shown below, leading to significantly underestimated values.

A high-speed 6-bit resolution digital-to-analogue converter (DAC) for generating four-level pulse amplitude modulation (PAM4) signals with high waveform quality is designed and fabricated using InP double-heterojunction bipolar transistor (DHBT) technology. The DAC outputs a clean PAM4 signal at 80 GBd and a sawtooth signal at 80 GS/s.

A push–pull silicon photonic Mach–Zehnder modulator (MZM) driver is presented which uses a switched capacitor approach to generate a ∼2 V peak-to-peak differential 4-level pulse amplitude modulation (PAM-4) signal. The driver chip includes a Gray encoder and retiming flip-flops. The switched capacitor approach allows driving the lumped silicon photonic MZM with reduced power consumption compared with the conventional approach of driving MZMs (with transmission line based electrodes) with a power amplifier. This is critical for upcoming short-reach link standards such as 400 Gbit/s 802.3 Ethernet. The chip was fabricated using a 65 nm CMOS technology and flip-chipped on top of the silicon photonic chip (fabricated using IMEC's ISIPP25G technology) that contains the MZM. Open eyes with 4 dB extinction ratio for a 36 Gbit/s (18 Gbaud) PAM-4 signal are experimentally demonstrated. The electronic driver chip has a core area of 0.11 mm² and consumes 236 mW from 1.2 to 2.4 V supply voltages. This corresponds to an energy efficiency of 6.55 pJ/bit including Gray encoder and retiming, or 5.37 pJ/bit for the driver circuit only.

The development of wafer-level vacuum-encapsulated low-voltage and high quality factor (Q) ring resonator is presented. The resonator is fabricated using microelectromechanical systems (MEMS) integrated design for inertial sensors process introduced by Teledyne DALSA Semiconductor Inc.. The resonator is designed to be operational with 5 V DC polarisation voltage in the breath mode of vibration at a resonance frequency of 10 MHz. The measured Q of the ring resonator exceeded 84,000.

A modified chelate precursor doping technique using high-purity materials and accurate gas flow control system is proposed to fabricate an efficient ytterbium-doped large-mode-area silica fibre for laser development. This technique enables to make homogeneous large-core preform with symmetrical shape, relatively low numerical aperture of ∼0.06 and large-core size of over 4 mm. Homemade preform was drawn into standard fibre for testing and fully characterised by electron probe microanalysis and time-of-flight secondary ion mass spectrometry. On the basis of two-stage master oscillator power amplifier system, 1 kW laser output with slope efficiency of 81.0% was realised at ∼1064 nm.

A novel full-range soft-switching full-bridge (FSFB) cycloconverter-type high-frequency-link inverter (CHFLI) with active snubber network is proposed. By adding an auxiliary inductor in primary-side DC/AC converter and adopting centre-tapped transformer structure, the proposed FSFB-CHFLI achieves zero voltage switching (ZVS) for all switches under different operating conditions from light load to rated load, which benefits with high efficiency and high switching frequency. The secondary-side active snubber network is utilised to recycle leakage inductor energy and suppress voltage spikes caused by the resonance of the leakage inductor and the parasitic capacitance of switch. The commutation overlap strategy is adopted to guarantee complete ZVS turn-on and ZVS turn-off of bidirectional switches. Experimental results of a high efficient and high switching frequency (200 kHZ) prototype are presented to verify the analysis results of the proposed FSFB-CHFLI.

To overcome the disadvantages of the required motion compensation in the traditional inverse synthetic aperture radar imaging of moving targets, a 2D single snapshot imaging method using a MIMO radar based on the sparse representation (SR) is proposed. It can simultaneously recover a real-time 2D image and avoid motion compensation. By exploiting the sparsity and data structure of the echo signals, a 2D SR model is established. The SR problem is solved based on the compressed sensing theory and the 2D smoothed L0 algorithm. Finally, the 2D image of the target can be reconstructed at low signal-to-noise ratio and high compressed ratio, which is advantageous for target recognition and classification. Compared with the existing 1D methods, the proposed method can directly recover 2D images and has lower computational complexity. Simulations are performed to verify the effectiveness of the method.

Multi-sub-bands stitching technique is an effective method to achieve ultra-high range resolution in synthetic aperture radar (SAR) system. However, sub-bands stitching error results in artefacts in multi-sub-bands SAR images, e.g. defocused targets, higher sidelobes, which seriously degrade SAR image quality and cannot be mitigated by weighting function. A novel stitching error estimation method was presented. The stitching error is modelled by regarding phase error as function of range frequency, which will be estimated and compensated to reach the maximum image sharpness. First, amplitude balance is applied to single look complex SAR image in range frequency domain. Subsequently, based on image sharpness, an iterative optimisation algorithm is designed to estimate and compensate the stitching phase error. Finally, experimental results using both real RADARSAT-2 and airborne SAR dataset validate proposed method perform well in arbitrary scenes, and it outperforms the existing methods.

Group sparsity based wide angle synthetic aperture radar imaging model is developed and propose a novel algorithm called backprojection based group complex approximate message passing to recover the anisotropic scene. Compared with conventional backprojection based complex approximate message passing algorithm for the recovery of isotropic scene, the proposed method accommodates aspect dependent scattering behaviour better and can produce better imagery. Simulated and experimental results are presented to demonstrate the validity of the proposed algorithm.

Binary coded decimal (BCD) to 7-segment decoder with oxide thin film transistors (TFTs) was implemented on a glass to display 7-segment display from BCD. The developed BCD to the 7-segment decoder with indium–gallium–zinc oxide thin film transistors was verified up to 1 kHz operation frequency under the power supply voltage of 5 V, and converted successfully 4-bit binary input code to 7-segment inputs. The binary output voltages were 0.4 V for the low and 4.1 V for the high at an operation frequency of 500 Hz, respectively. The output signals of the developed 7-segment decoder matched well the BCD to the decimal values. The result showed that oxide TFT can be used for the integrated BCD to 7-segment decoder for the various sensing applications, particularly for wearable devices and the integrated bio sensing platform.

A non-stoichiometric (NS) GaAs layer by the means of terahertz (THz) emission spectroscopy is investigated. THz emission azimuthal dependencies and THz pulse amplitude dependence on the excitation angle were measured. Obtained results were explained by the existence of parallel to the sample surface components of THz radiating electric dipoles. The results were compared with those gained investigating GaAs nanowires. In addition, it was shown that a NS GaAs layer could be a very promising material for a compact bias-free THz emitter with good spectral characteristics.

The restricted isometry constant (RIC) bound for the recovery of a sparse signal with l ₂ bounded noise by orthogonal matching pursuit algorithm is studied. We show under our weaker condition on the RIC of sensing matrix and the minimum magnitude of the non-zero components, the support of the unknown signal can be recovered exactly under l ₂ bounded noise. Our results are better than the best existing ones.

An extremely simple, low-cost, chipless RFID reader is demonstrated. The reader consists of only a single voltage controlled oscillator (VCO) as the detector front end. The information from the chipless RFID tag appears as a low-frequency variation on the VCO DC bias supply which is readily detected and demodulated. Experimental results are shown for successful detection of a 10-bit RFID tag, operating over the frequency range 2.4–3.4 GHz. The results when compared with those taken from a vector network analyser (VNA) prove that the VCO detector can provide a similar level of performance to the more sophisticated VNA arrangement. The proposed solution provides a significant simplification of the chipless RFID reader.

A high-performance waveguide bandpass filter operating at W-band is presented. This folded fourth-order filter with quasi-elliptic response is developed by introducing cross-coupling and source–load coupling, while maintaining a compact construction for simple computer numerical control (CNC) milling process. The filter fabricated within aluminium block shows an insertion loss of about 1.2 dB in a 3 dB fractional bandwidth of 5.5% from 90.1 to 95.2 GHz, which are very close to the simulated results in the full W-band.

Closed-form expressions for the bit error rate (BER) in an interference-limited wireless network are derived. Users are distributed according to a Poisson point process and communicate over a Nakagami fading channel using the widely employed Gray-coded quadrature amplitude modulation. The way how interference influences the BER provides insight into the interference control mechanism to be implemented and helps to analyse the achievable data rates.

A distributed algorithm is proposed which routes packets to minimise the expected latency in arbitrarily connected mesh networks, where each link has a set transmission rate. It is proven that the proposed algorithm converges to the global minimum. Initial simulations demonstrate the effectiveness of the proposed algorithm relative to current methods based on Dijkstra's algorithm.

Quadrature bandpass sampling (QBPS) offers a reduced complexity alternative to sampled quadrature (Q) downconversion. However, if the in-phase and quadrature sequences produced are reconstructed at the baseband in the same manner, distortion will result. The effects of this distortion are examined with a view to establish the best way to process the QBPS sequences.