A multichannel blind source separation algorithm based on the multichannel non-negative matrix factorisation (NMF) model and an alternating least squares (ALS) method is developed. To develop the proposed algorithm, the multichannel NMF (MC-NMF) model is modified with stacked matrix notation. In the model, all parameters – frequency basis, time basis and mixing matrix – are estimated using the ALS method. The proposed MC-NMF algorithm is evaluated using an ‘underdetermined speech and music mixture’ dataset from the International Signal Separation Evaluation Campaign 2013 (SiSEC 2013). Experimental results show that the proposed algorithm outperforms the conventional NMF algorithms.

A circularly polarised cut ring microstrip antenna is proposed. The antenna realises circular polarisation and obtains high gain. It is characterised by simple construction and feed mode, and it is not sensitive to the feeding position, which means it is easy to be matched. A study of the different geometric parameters of the antenna and their effect on the performance of the antenna has been conducted. The designed antenna works at about 3.4 GHz, and the results show good performance with a −10 dB return loss bandwidth of ∼19.6%, a 3 dB axial ratio a bandwidth of ∼4.2% and a circularly polarised gain of about 10.97 dB. The measured results agree well with the simulated results.

The security gap of a wireless network composed of two legitimate nodes and one eavesdropper, all provided with multiple antennas, is evaluated. The use of transmit antenna selection combined with frame scrambling may lead to gaps <0 dB, under feasible scrambling depths and a practical number of transmit antennas is shown.

A frequency-agile microstrip patch antenna printed on a biased nematic liquid crystal (N-LC) substrate is accurately modelled. The dielectric properties of the N-LC are controlled through the strength of the bias voltage. The model is based on the solution of Poisson's equation coupled to a nonlinear partial differential equation (PDE) describing the orientation of the directors in a non-homogeneous electric field. The coupled problem was solved using an iterative finite difference (FD) scheme. The obtained numerical results are compared and verified against measurements already published in the literature.

A phase variation detection scheme based on a SSB-AM detector for the active phased array antenna is introduced. Since the phases of arrayed elements for the active phased array antenna vary unavoidably with increase in the surrounding temperature, such shifts should be detected and compensated accordingly, for maintaining the accuracy of beam direction radiated from the phased array antenna. Simulation results show that the proposed scheme is quite feasible.

A differentially driven ultra-wideband (UWB) polarisation diversity antenna with dual notch bands is presented for the first time. The antenna consists of a chamfer square slot and two differential pairs being orthogonal to achieve polarisation diversity performance over the UWB. The proposed antenna has a wide impedance bandwidth from 2.75 to more than 11 GHz for differential reflection coefficients less than −10 dB, and a high differential port-to-port isolation of less than −40 dB. Dual band-rejected operation to filter the 3.5 GHz WiMAX and 5.5 GHz WLAN bands is obtained by employing two different methods. All these features make the proposed antenna very suitable for applications in UWB wireless communication systems.

Bayesian integration is thought to be used by the brain for optimal decision-making based on information from different sources. Recent evidence indicates that the hippocampal place cells use this mechanism to integrate information at the level of a single cell as opposed to that at the network level as postulated earlier. Therefore a synapse circuit is proposed, which can perform Bayesian integration on three inputs and present results from its implementation in silicon.

With the rising number of elderly people, the cancer rate is also increasing. Thus, to detect cancer in its early stages is very important for increasing survival rates because cancer is one of the leading causes of death. Therefore, diagnosing cancer with a radio frequency (RF) coil that is used to obtain high-quality medical images from magnetic resonance imaging (MRI) systems is proposed in order to reduce the cost and time needed for the test. Specifically, an RF coil can sense a change in the electrical characteristics of body tissue, such as permittivity and conductivity. This pre-study shows that RF coils without an MR magnet can be used to determine the difference between normal and abnormal tissues (i.e. a tumour).

A fully integrated 0.9 V, 8b, 300 MHz pipelined analogue-to-digital converter (ADC) using healed transistors and charge-steering op-amps in 180 nm CMOS technology is presented. The proposed ADC employs the modified current-driven bulk (CDB) method as a healing technique to reduce the threshold voltage (V _th) of transistors in order to improve the overall performance. The fabricated ADC achieves an SFDR of 59.1 dB and an SNDR of 42.9 dB while dissipating 2.56 mW from the 0.9 V power supply. These results yield an FOMW of 74.8 fJ/conversion step and an FOMS of 150.6 dB.

Time-to-digital converters (TDCs) are an important circuit block in time-of-flight sensors, fluorescence lifetime sensors, and self-calibrating digital circuits. Fine-resolution TDCs are usually built with chains of delay elements, but this architecture requires large area, conversion time, and power consumption. A novel compact TDC architecture based on the cyclic comparison algorithm is presented, which implemented and tested in the TSMC, 0.35 μm process within a 200 × 200 μm area is demonstrated that the proposed TDC achieves a conversion rate of 10 ns/bit and sub-picosecond resolution. The measured power is 0.7 mW, taking 100 ns for each bit.

A two-stage (Miller) operational amplifier (opamp) with both class AB input and output stages is introduced. It has a well-controlled quiescent current and generates dynamic output currents of up to a factor 45 times larger than the quiescent current. It uses very compact circuitry with small static power consumption in order to achieve class AB–AB operation and can operate with a low supply voltage. Experimental results of a test chip fabricated using 0.18 μm CMOS technology and simulations in 130, 90, 65 and 45 nm verify the proposed circuit.

A low-cost memory data scheduling method based on two N/2-depth single-port memories is proposed for reconfigurable fast Fourier transform (FFT) bit-reversed data reordering tasks. To make single-port memories have the equivalent ability to read and write data simultaneously, two types of read and write address generation methods are proposed. Based on the proposed data scheduling method, the bit-reversal circuits are designed for continuous data reordering tasks. The proposed bit-reversal design is implemented for a maximum 8 k flexible length FFT processor. Compared with the other two conventional methods, the proposed bit-reversal method can reduce memory area cost by 53.8 and 46.1%, respectively.

A squaring circuit is introduced that boosts the tail current source of an opamp to improve its slew rate. It operates as a differential voltage magnitude detector, which generates opamp tail currents proportional to the magnitude (square) of the opamp's differential input voltage. Experimental results from a fabricated test chip verify current and slew rate enhancement between 900 and 1400% with respect to its initial value with <20% static current increase.

A closed-loop system for the central pattern generator (CPG)-based locomotion control of biped robots that operates in the joint space is presented. The proposed system has been designed to allow biped robots to walk on unknown sloped surfaces. Feedback signals generated by the robot's inertial and force sensors are directly fed into the CPG to automatically adjust the locomotion pattern over flat and sloped terrain in real time. The proposed control system negotiates sloped surfaces similarly to state-of-the-art CPG-based control systems; however, whereas the latter must continuously solve the computationally intensive inverse kinematics of the robot, the proposed approach directly operates in the joint space, which makes it especially suitable for direct hardware implementation with electronic circuits. The performance of the proposed control system has been assessed through both simulation and real experiments on a NAO humanoid robot.

A single-plane electrical capacitance tomography (ECT) sensor is usually used to visualise dielectric material distribution by providing two-dimensional (2D) images. The imaging of a metallic object inside a dielectric material is reported and the feasibility of 3D imaging based on the fringe effect of a single-plane ECT sensor is demonstrated. Experimental results are given.

In three-dimensional (3D) video, a compressed depth map usually has large distortions along-boundaries, leading to object deformation and artefacts in synthesised views. A so-called candidate values based boundary filtering (CVBF) with low computational complexity by filtering only some detected unreliable pixels along the boundaries is proposed. Assuming that the smooth regions consist of reliable pixels, CVBF selects an appropriate candidate value to replace each unreliable pixel based on both the nearest reliable pixels and the mean values of surrounding regions. Experimental results show that synthesised views with CVBF-filtered depth maps are better than existing joint trilateral filtering, the depth boundary reconstruction filter and the adaptive depth truncation filter.

A novel approach is proposed for online evaluation of video tracking without ground-truth data. The temporal evolution of the covariance features is exploited to detect the stability of the tracker output over time. A model validation strategy performs such detection without learning the failure cases of the tracker under evaluation. Then, the tracker performance is estimated by a finite state machine determining whether the tracker is on-target (successful) or not (unsuccessful). The experimental results over a heterogeneous dataset show that the proposed approach outperforms related state-of-the-art approaches in terms of performance and computational cost.

A new wavelet-based interpolation algorithm to improve the performance of colour filter array (CFA) interpolation is exploited. The purpose of a CFA is to filter a single colour in digital still camera images. A CFA interpolation can then restore full colour to images captured by the CFA. The proposed classifier can effectively restore edge information and reduce the complexity of computation.

The superpixel, as an important pre-processing technique, has been successfully used in many vision applications. Introduced is a fast superpixel method called iterative edge refinement (IER). The image was first initialised as regular grids, and then concentration was on unstable pixels and relabelling them iteratively so called unstable pixels, are edge pixels around the moving boundary. It is found that the unstable pixels decrease rapidly during the iterative process, which results in a high speed-up. Experimental results on the Berkeley BSDS500 dataset show that IER achieves a segmentation performance comparable with the state-of-the-art, and moreover, runs in real-time on a single Intel i3 CPU at 2.5 GHz.

A novel image-stitching algorithm is proposed that uses the chaos-inspired dissimilarity measure. Previous approaches to image stitching generally employed invariant local features and random sample consensus (RANSAC), to verify image matches. In panoramic stitching, however, RANSAC is highly sensitive to illumination difference between the pair of images stemming from two different exposures, which essentially results in mismatched pairs, leading to poor stitching performance. By applying chaos theory, the contextual change of an image becomes chaos-like, and results in a complex fractal trajectory in phase space. The specific chaos behaviour between a pair of images is exploited, whereby the resulting phase space exhibits strong invariance to illumination changes. Accordingly, the chaos-inspired dissimilarity between images is measured, thereby the matched pairs are robustly found under the presence of illumination difference. Representative performance experiments demonstrate significant improvements over the conventional method.

Multimodal biometric systems have many advantages over single-modal biometric systems, e.g. higher recognition accuracy and security level. However, for most existing multimodal biometric systems, experiments are conducted using the unreal multimodal databases in which no samples of different biometric modules are from the same person. For example, a fingerprint sample of person A and a biometric face sample of person B will be combined to form a sample of the joint fingerprint module and face module. A multimodal biometric system is designed and tested, which is made up of two common biometrics, face and fingerprint, using a real multimodal database (a sample of the joint fingerprint module and face module is formed from the fingerprint and face of the same person) and two unreal multimodal databases. From the experimental results it is observed that there is a large discrepancy between the system performances evaluated with the real and unreal multimodal databases. This indicates that ignoring the influence of feature dependency, which has been a common practice in evaluating multimodal biometrics systems, can produce misleading system performance evaluation results.

An efficient screen content video coding method to adaptively turn on/off filters used for intra-prediction is proposed. A block is classified into two categories based on a statistical property of a block and a transform coding mode in the compressed domain. Specifically, the Mahalanobis distance (MD) between the estimated probability density distribution and prediction samples in the left and top boundaries of the block to be coded and its transform coding mode is used. The set of the filters are disabled depending on the condition. Experimental results demonstrated that the proposed method outperforms the state-of-the-art video coding standard, i.e. the high-efficiency video coding/range extension (HEVC/RExt), in terms of rate-distortion (R-D) performance.

An accurate stereo matching method developed by exploiting the two techniques, discrete-coded structured-light projection and image-guided cost volume filtering, is proposed. The former increases the distinctiveness of pixels by projecting a discrete pattern to the scene, and the latter helps to recover accurate object boundaries. In addition, a previous fast cost volume filtering approach is extended to better preserve slanted surfaces, and a suitable post-processing algorithm is also suggested for the proposed method. The performance of the proposed method is experimentally verified by comparing the results with those of other algorithms qualitatively and quantitatively in an indoor environment.

Traditional frontal face image synthesis based on the ℓ ₁-penalty has achieved remarkable success. However, the ℓ ₁-penalty on reconstruction coefficients has the drawback of instability when processing high-dimensional data (e.g. a facial image including hundreds of pixels). Moreover, the traditional ℓ ₁-penalty-based method requires consistency between the corresponding patches in frontal and profile faces, which is hard to guarantee due to self-occlusion. To overcome the instability problem of the traditional method, an extension of the ℓ ₁-penalty-based frontal face synthesis method, which benefits from the nature of the elastic net, is presented. 3 addition, to enhance the aforementioned consistency, a neighbourhood consistency penalty is imposed onto the reconstruction coefficients using the connected neighbour patches of the current patch. Furthermore, to ensure the synthesised result faithfully approximates the ground truth, a sparse neighbour selection strategy is introduced for finding related neighbours adaptively. Experimental results demonstrate the superiority of the proposed method over some state-of-the-art methods in both visual and quantitative comparisons.

Cross-correlation of binary sequences is a technique used in many applications. A method is presented whereby fast cross-correlation can be employed in applications that initially use the parameters of sequences derived from difference sets. The simple idea is to replace the difference set sequence with a sequence that has similar parameters, but for which a fast cross-correlation method exists. Experimental tests using a computer confirm the time savings of this method.

The choice of the data type representation has significant impacts on the resource utilisation, maximum clock frequency and power consumption of any hardware design. Although arithmetic hardware units for the fixed-point format can improve performance and reduce energy consumption, the process of tuning the right bit length is known as a time-consuming task, since it is a combinatorial optimisation problem guided by the accumulative arithmetic computation error. A novel evolutionary approach to accelerate the process of converting algorithms from the floating-point to fixed-point format is presented. Results are demonstrated by converting three computing-intensive algorithms from the mobile robotic scenario, where data error accumulated during execution is influenced by external factors, such as sensor noise and navigation environment characteristics. The proposed evolutionary algorithm accelerated the conversion process by up to 2.5 × against the state-of-the-art methods, allowing even further bit-length optimisations.

A new methodology for sparse signal acquisition using a multi-comparator-based integrate-and-fire sampler is presented. By employing the randomness of comparator voltages, the original analogue signal is converted into a series of binaries and is guaranteed to be precisely recovered from these measurements. The proposed scheme operates with a sub-Nyquist rate, which requires neither a high-speed linear feedback shift register nor an accurate analogue-to-digital converter. The experimental results demonstrate the effectiveness of the proposed scheme.

Based on convex programming for optimisation, the optimal superimposed (SP) training signal design is proposed for spatially correlated multiple-input–multiple-output (MIMO) channels in the presence of correlated symbols and coloured Gaussian noises. Simulation results show that the proposed training design can effectively estimate the channel and outperforms the existing designs.

The performance of an energy detector is analysed over an η − μ fading channel using the probability density function (PDF) of the received instantaneous signal-to-noise ratio. The η − μ is a generalised multipath fading channel that describes the non-line-of-sight wireless communications scenario. Novel, general, exact and closed-form analytic expressions for both average detection probability and the average area under the receiver operating characteristics curve are derived.

A random code is a rateless erasure code with a generator matrix of randomly distributed binary values. It encodes a message of k symbols into a potentially infinite number of coded symbols. For asymptotically large k, the tail bound in Kolchin's theorem asserts that the high probability of complete decoding (PCD) is attained almost surely with k + 10 coded symbols. However, for small values of k (short messages) it is unclear if such asymptotics are useful. That the random codes achieve a high PCD with k + 10 coded symbols for small k is demonstrated. In particular, a set of lemmas is established and show that the PCD converges to five decimal digits after k = 30. A theorem extending Kolchin's work is formulated and the theorem is used to explain the complete decoding probabilities of random codes in short messages.

A blind spectrum sensing method based on the goodness-of-fit (GoF) test using the likelihood ratio is studied. In the proposed method, the χ ² distribution is used for GoF testing. The performance of the method is evaluated through Monte Carlo simulations. It is shown that the proposed spectrum sensing method outperforms the GoF test using Anderson-Darling and the conventional energy detection tests in the case of a low signal-to-noise ratio.

An unsupervised binary hashing (UBH) method is proposed. To preserve the local and Euclidean metric structures in the reduced feature space, it performs the dimensionality reduction (DR) by using the orthogonal locality-preserving projection. In addition, it minimises the error between the generated binary hash codes and low-dimensional feature vectors that are obtained in DR. To minimise the quantisation error, the binary hash codes are generated using the optimal rotation and offset. Experimental results show that the proposed UBH method has better performance than other existing methods in terms of the mean average precision and recall–precision curve.

A 500 GHz system for gas spectroscopy is presented, which includes an integrated SiGe 4 × 1 transmitter (TX) array, a Golay cell as a detector and a 1.9 m-long gas absorption cell. The local oscillator (LO) of the TX array is controlled by an external phase-locked loop, whose reference frequency is swept. The four TX branches involve frequency quadruplers (x4). The TX branches are fed by a 120 GHz power division network, which is connected to the LO. The estimated radiated output power of the TX array is −7 dBm at 500 GHz. The absorption spectrum of gaseous methanol is shown for 494–500 GHz.

A novel broadband substrate-integrated waveguide (SIW) T-junction with an arbitrary power-dividing ratio is proposed. Three inductive posts are designed to adopt flexibility for the equal output T-junction to obtain a wide impedance bandwidth. To realise the unequal power-dividing ratio over a wide bandwidth, the SIW coupler is integrated with corner structures and a novel T-junction structure is formed. Three T-junctions with different power division ratios (1:1, 1:4 and 1:8) at a centre frequency of 6 GHz are simulated, fabricated and measured. The measured bandwidths are 60, 53 and 63.3%, respectively.

A novel dual-band transmission line with flexible phase shifts is presented. To realise dual-band operations, the proposed transmission line is constructed by series-connected coupled lines and open-ended stubs. Using this structure, flexible characteristic impedances and electrical lengths can be designed to operate at two frequencies. Moreover, the proposed dual-band transmission line features a wide range of realisable frequency ratios and a flexible structure. For practical applications, a planar dual-band 3 dB branch-line coupler operating at 2/5.2 GHz is designed using the proposed dual-band transmission line. The simulation and measurement results agree very well with the design theory.

A wideband patch directional coupler is proposed. The coupler is designed based on the non-uniform mushroom structure with unique characteristics. The current distribution within the patch can be controlled by the mushroom cells underneath for wideband property. An 8 dB directional coupler has been designed, fabricated and measured for verification. It exhibits good return loss, small coupling coefficient variation and quadrature phase difference among the output ports over a wide bandwidth of 74.6% centred at 8.45 GHz.

A compact and high selective lowpass filter (LPF) with wide stopband is presented using coupled rhombic stubs. The proposed LPF unit is constructed by loading a rhombic stub on a transmission line. Then, a folded three-element LPF is proposed to achieve compact size and high selectivity by introducing coupling between adjacent rhombic stubs. The operating mechanism of the filter is investigated and explained, by adopting the physically-based LC-equivalent circuit model. The implemented final LPF exhibits a wide stopband of up to 11.5 f _c with a rejection level of better than 35 dB. Furthermore, the final LPF features a compact size of 0.12λ _g × 0.10λ _g, where λ _g is the guide wavelength of f _c, and a very high figure-of-merit (FOM) of 27 142.

Tunable filters using the TE₀₁₁ mode have slot irises for coupling between cavities. Unless the slot iris is appropriately designed, the coupling value of the iris varies as an operating frequency changes and the filter performance deteriorates as a result. In this reported work, it was found that the frequency-dependent coupling characteristic of the slot iris can be minimised by locating the iris appropriately. Why the coupling of a slot iris changes when the operating frequency is tuned is explained and how to find the optimum location of the slot iris for minimum variation of the coupling value is presented. The proposed theory is verified by full-wave EM simulations and experiments with a Ka-band two-pole filter.

Light-emitting diode (LED) access point (AP) scheduling can provide both significant performance gains and flexible user access for visible light communications. However, the scheduling for multiple moving users, which requires adaptive LED AP scheduling for user movements and is practical in common scenarios, has so far rarely been studied. An incremental scheduling scheme is proposed to introduce a time division scheduling framework to solve the scheduling problem with multiple moving users. The proposed scheme consists of two phases: global scheduling and local scheduling. In the global scheduling phase, a scheduling scheme based on graph theory is proposed to assign users to different timeslots to eliminate inter-user interference. In the local scheduling phase, the result of global scheduling is adjusted for user movements. Simulation results show that the proposed scheme improves system capacity with reduced complexity.

A multi-layer inductor is proposed to achieve high inductance with moderate Q-factor values. The development of integration of devices technology in radio-frequency (RF) has increased the importance of on-chip inductors. In the literature, the planar inductor, the three-dimensional (3D) inductor with constant width and the 3D inductor with variable width are reported. Using the basic concept of multi-layer technology in very large-scale integration (VLSI) system design and considering lambda rules, the proposed inductor is designed. The inductance of the proposed inductor is nearly 37–45% higher compared with reported inductors with a moderate quality factor. This inductor is realised using 180 nm scale technology with an area of cross-section 10 × 10 µm². Results are presented using the IE3D EM field solver with the help of series RL and shunt RC lumped Pi model.

Fully transparent tin-doped zinc oxide thin-film transistors (TZO TFTs) were successfully fabricated on glass substrate by radio-frequency sputtering at room temperature. In this reported work, TZO is adopted as the channel layer, SiO₂ as the gate insulator and indium tin oxide as gate and source/drain electrodes. The surface morphology and crystallographic structure of the TZO films were evaluated by scanning electron microscopy and X-ray diffraction, respectively. Sn atoms are found to successfully replace Zn sites in the lattice and form stable Sn–O bonds. Sn dopants and adding O₂ during the TZO channel deposition can enhance the device performance. The as-fabricated TZO TFT exhibited excellent electrical and optical properties. Hence, TZO can be a promising candidate for the next generation driving active-matrix flat panel displays.

A low part count, efficient quasi-resonant light-emitting diode driver is proposed. The proposed driver relies on a capacitive safety isolation barrier, which eliminates the need for a bulky isolation transformer; thus, the footprint area can be reduced. Operation frequencies of 100–350 kHz further contribute to miniaturisation of the proposed driver. The feasibility of the proposed topology is verified by simulation and experimental results.

High-power and high-linearity photodiodes (PDs) are of critical importance to achieve high-efficiency analogue fibre links. A small-signal analysis is utilised on the nonlinear responsivity of the modified uni-travelling-carrier PDs to understand the theoretical limitation on the third-order output intercept point (OIP3) of the link. It is theoretically shown that a nonlinear responsivity depending on both the voltage and the current can give rise to an enhanced OIP3 at certain bias and current values.

A novel interferometric configuration for orbital angular momentum (OAM) mode multiplexing/demultiplexing, based on the image transformation property of pairs of cylindrical lenses and without any splitting loss, is proposed. The effectiveness in mode demultiplexing has been experimentally proven by performing bit error rate measurements for a 20 Gbit/s mode division multiplexing communication system where two modes with different values of OAM, corresponding to the angular indices l = 0 and 1, respectively, are transmitted.

Generation of optical pulse trains using semiconductor lasers has attracted significant attention due to their applications in optical communications and signal processing. A pulse generator based on the nonlinear dynamics of an optically injected distributed feedback laser is presented. The proposed system does not require electrical excitation and can be configured to operate in a periodic or aperiodic pulsation regime by controlling the injection conditions. Experiments show periodic pulsation with a repetition rate of 1.034 GHz and aperiodic pulsation with an average repetition rate of 5.618 GHz.

The use of a silicon (Si)-photodiode (Si-PD) operating in photovoltaic mode as a tunable very high-sensitivity phase detector of light power variations is demonstrated. This result is reached by applying to the Si-PD an electrical modulation through an AC excitation signal without a DC reverse bias. This allows employing the synchronous demodulation technique for phase detection that shows much better performances with respect to the conventional amplitude measurements, mainly overcoming the issues related to the electrical noise and the resolution limitation due to the selected full scale. The phase variations to be detected occur between the modulating signal and the one provided by the Si-PD as a function of the light power variations on its sensitive area. The proposed approach notably simplifies both the electronic circuitry and the optical setup, minimising the detection system complexity and size. Experimental results demonstrate that it is possible to achieve phase detection sensitivity, with respect to light power variations, of up to 410°/μW as a function of the Si-PD settable operating conditions. Using a standard commercial lock-in amplifier with a 0.01° phase resolution is possible to obtain a light power resolution of up to 25 pW.

Proposed is a helical piezoelectric structure for a highly stretchable energy harvester to be applied on the human body. The proposed device consists of two counter-wound helical structures around a zcore structure made of an elastic fabric string. The inner fabric helix is used to separate the outer piezoelectric helix from the core to obtain a highly stretchable device. When stretched by 60% of its initial length, the device generates a maximum output voltage and power of 140 V_p-p and 0.6 mW, respectively, at an operation frequency of 4 Hz.

A novel method is proposed to effectively solve the challenging problem of direction-of-arrival (DOA) estimation for closely spaced correlated signals. A centro-Hermitian extended matrix is exploited to double the number of data samples, and then is transformed into a real-valued data matrix. An improved sparse Bayesian learning scheme is utilised to estimate DOAs by recovering the real-valued jointly row-sparse solution matrix with a reduced computational burden. The proposed method not only provides increased estimation accuracy but also has improved angular separation performance. Simulation results validate the effectiveness of the proposed method.

In high-resolution radar imaging, there is inevitable migration through range cells (MTRCs) in an inverse synthetic aperture radar (ISAR) image due to the manoeuvrability of the target. In the case of sparse aperture (SA) measurement, it is generally difficult to accurately correct MTRCs to degrade the imaging performance. An approach of SA-imaging jointly with MTRC correction for manoeuvring targets is presented. Under a chirp-Fourier dictionary by involving MTRCs, the ISAR image formation is treated as a sparse-driven optimisation to overcome the SA. Experiments based on the measured data are performed to confirm the effectiveness of the proposed algorithm.

The two-dimensional parity check is the optimum single-error-correction code in terms of speed. In this reported work it is employed to develop two sliding schemes for through-silicon-via cluster error correction in three-dimensional ICs. For k bits of source data, the one-dimensional sliding scheme can correct a single cluster error up to about √k bits and more extra discrete errors can be corrected by the two-dimensional sliding scheme. Experiments show that for several hundreds of through-silicon vias (TSVs), two trees of 3-level 2-input exclusive-OR (XOR) gates are almost optimised to encode and decode each interconnect, and the time penalty can be controlled within about 1 ns.

A mathematical framework to obtain a generalised energy-efficient trade-off model for generic wireless sensor networks (WSNs) while attaining sensing node synchronisation at a given network-wide estimation error threshold is presented. The model outputs both a theoretical optimal solution as well as a set of sub-optimal solutions to cater for real-world WSN designs. The robustness of the proposed framework is examined with an example in which randomly deployed sensors are affected by path-loss and uncorrelated Rayleigh fading effects.

Device-to-device communication fulfils its potential in terms of high resource utilisation, thus it has been a hot topic in the recent long-term evolution standardisation process. The general scenario with multiple resource pool multiplexing instead of the one-time reusing is considered. Meanwhile, the optimisation target focuses on device energy efficiency under certain system throughput insurance rather than the traditional system throughput. A modified genetic algorithm-based scheme is applied to address the facing non-deterministic polynomial-time hard problem with higher convergence and lower complexity.

A novel algorithm for time of arrival (TOA) estimation for OFDM-based transceivers is presented. The algorithm processes the sampled baseband signal to obtain a high-resolution estimate of the TOA of the OFDM symbol. In the first step, the algorithm obtains a sample-resolution estimate of the TOA by finding the peak of the absolute value of the cross-correlation of the in-phase and quadrature received signals with the known transmitted symbol. In the second step, the algorithm refines this estimate to sub-sample resolution by estimating the phase delay of the received signal based on the gradient of a linear fit to the phase difference between the transmitted and received sub-carriers (in the frequency domain). The algorithm was applied to the long training sequence (LTS) symbol of the IEEE wireless local area network (WLAN) 802.11 g preamble. In real-world experiments, the algorithm was found to achieve a mean TOA estimation error of 49 cm in a low multi-path line-of-sight environment for ranges of 1–7 m.

Multiuser multiple-input–multiple-out (MU-MIMO) plays a key role in the widely adopted 3GPP LTE standard for wireless cellular networks. Although exact and asymptotic sum-rate results are well known, the problem of obtaining intuitive analytical results for medium signal-to-noise ratios (SNRs) is still not solved. As a result of the present reported work, the bend point is proposed, which quantifies the transition between low and high SNR, i.e. the beginning of the high SNR region. The bend point is derived for MU-MIMO with zero-forcing precoding and is obtained, that it is intimately related to the intercept of the high SNR asymptote with the zero sum-rate line. Using this result, a new approximation of the sum-rate at the bend point it is shown providing a useful rule of thumb for the effect of increasing the number of antennas at medium SNR.