Multi-antenna-enabled terminal devices are required to comply with the standards for limiting human exposure to electric fields. However, when compared to the traditional single-antenna terminals, a comprehensive evaluation of specific absorption rate (SAR) for multi-antenna terminals is impractical. This is because both the power allocation and the phase of the electric fields from different antennas are arbitrary in practical multiple-input–multiple-output (MIMO) operation, hence requiring exhaustive evaluation over all possible cases. In this context, first, the time-averaged simultaneous peak SAR (TASPS) is proposed as an efficient metric to evaluate the exposure when more than one antenna is transmitting simultaneously. Then, it is analytically derived that TASPS will be below a given exposure limit, as long as the stand-alone peak SAR for each antenna is smaller than that limit. Thus, SAR evaluation is greatly simplified since only the stand-alone SAR needs to be measured. Several examples of dual-antenna mobile handsets are shown to illustrate and validate the analytical result.

The design, development and characterisation of an inclined waveguide slot-based circularly polarised (CP) omnidirectional antenna at Ka-band frequency are described. The antenna consists of inclined slots on a circular waveguide and a coaxial feeding probe. All the radiating slots are fed by the TM₀₁ mode of the circular waveguide to generate the omnidirectional pattern. Inclination of slots has been used to generate circular polarisation. The designed antenna has omni coverage in the azimuthal plane and −10° to +45° coverage in the elevation plane. The antenna has been simulated on finite element method-based ANSYS high-frequency structure simulator (HFSS) EM simulator software using proper boundary conditions. The proposed antenna has the advantages of being robust, having wide coverage, being easy to fabricate (being in waveguide configuration) and is suitable for mass production. The measured axial ratio lies well below 2.8 over the horizontal plane. A voltage standing wave ratio of 2.0:1 has been achieved over the frequency band of 37.9–38.55 GHz and the minimum omni gain of the antenna is 0 dBi over the frequency band as well as over the coverage.

Proposed is a simple technique to enhance the bandwidth of a planar monopole antenna with overall dimensions of 30 × 10 mm². With the proposed method, based on a modified ground plane and a loop feeding structure, the −6 dB bandwidth can be enhanced by ∼50% compared to the basic structure. Based on the simulation results, the antenna achieved a total efficiency higher than 70% on the entire band and the maximum realised gain varied between 2 and 4.8 dB. A prototype has been realised, and good agreement has been obtained between the measured and simulated results.

A cytomorphic circuit that can mimic gene expression regulation mechanisms is presented. It is shown that this circuit can efficiently predict the cellular response of the bacterium Escherichia coli in real time. The simulation outputs of the circuit are compared with biological experimental results. The significant similarity between these results shows that the circuit can be used to predict cellular malfunctioning within microseconds.

A new low-power rail-to-rail voltage-controlled quadrature oscillator is presented. This oscillator was implemented to provide the frequency deviation of frequency-shift-keying (FSK) modulation in implantable radio-frequency (RF) transceivers. The quadrature oscillator circuit generates differential in-phase and quadrature-phase (I and Q) signals in a two-stage ring configuration. The proposed structure of delay cells and the start-up circuit were implemented using IBM 130 nm CMOS technology. The frequency can be tuned between 300 kHz and 11.57 MHz by varying the supply voltage from 0.35 to 0.9 V. An average current of 5.5 µA (2.5 µW) was consumed to generate rail-to-rail differential quadrature signals with a frequency of 2 MHz as the target operating point dedicated to low-power implantable transceivers.

Recently, minimum variance beamforming (MV BF) has been actively investigated as a method to improve the performance of an ultrasound system beamformer, especially in terms of both the lateral and contrast resolution. However, since the inverse spatial covariance matrix must be calculated, a severe problem with the method is the prohibitive computational complexity. Among numerous attempts to overcome the problem, notable ones are the fast MV BF method based on principal component analysis and beam space adaptive beamforming. The two are similar in transforming an original signal in the element space to the other domain using an orthonormal basis matrix and approximating the covariance matrix with dimensionality reduction in the transformed domain, hence simplifying the inversion of the matrix. A new method that uses the Legendre polynomial as the basis matrix for such transformation is proposed. The efficacy of the proposed method is verified through Field II simulation. Computer simulation results show that the proposed method is better than or almost equal to the above two methods in the approximation error and the lateral response.

A digitally controlled oscillator (DCO) suitable for multi-standards radio-frequency (RF) operation is presented. It has an LC topology using an active inductor based on CMOS controllable inverters. The tunability of the oscillator frequency is ensured by varying the digital word applied to the inverters’ control voltages. The proposed DCO has a small area and exhibits a high-frequency tuning range while achieving low power consumption with good stability against process variations.

A logarithmic converter employing the proposed temperature compensating method based on a master–slave control is presented. With the help of a raised master–slave circuit, the proportional to absolute temperature (PTAT) coefficient of the logarithmic converter is compensated by that of the PTAT current in the bandgap reference, which makes the CMOS implementation of the logarithmic converter employing no external component possible. The logarithmic converter provides a 45 dB linear range with < 3 dB error as the temperature varies from 0 to 90°C.

A dual-mode adaptive method to provide a wide-range linear sensing characteristic over various resistive sensors is presented. A high-R mode acts as a resistance-to-digital converter without an analogue-to-digital converter (ADC), and a low-R mode utilises an adaptive current source to keep the required ADC resolution below 8 bits. A prototype of the dual-mode sensor interface was fabricated in a 0.18 μm CMOS process, and its measured coverage of sensor resistance was from 750 to 1.2 MΩ. The power dissipation with a 1.8 V supply was 2.6–3.1 μW in the high-R mode and 0.31–2.1 mW in the low-R mode.

The high-frequency characteristics of high electron mobility transistors applying AlGaN for a channel layer (AlGaN channel HEMTs) with greater impacts of alloy disorder scattering than those in conventional HEMTs with a GaN channel layer (GaN channel HEMTs) are investigated. The obtained electron saturation velocity was 4.7 × 10⁶ cm/s and the cutoff frequency was 7 GHz in the AlGaN channel HEMTs with a gate length of 1 μm. These results are promising for several gigahertz band operations of AlGaN channel HEMTs.

Three-dimensional (3D) dynamic random-access memory (DRAM) with TSVs has been proposed due to continuous demands for low-power and high-density memory without IO loading limitation. However, the process difference among the stacked dies causes the timing mismatch of internal signals. To remove signal confliction and reduce signal skews among the stacked dies, the simultaneous process self-calibration scheme is proposed. The stacked dies using the proposed scheme detect the slowest signal among the stacked dies and internal signals are aligned with the slowest signal at the same time. The time for aligned operation is within one read loop and the scheme is turned off after calibration to reduce additional standby current. The 3D double-data rate 4 (DDR4) DRAM using the proposed scheme is operated over 2133 Mbit/s at 1.2 V.

A novel pose compensation framework based on a new type of explicit loop closing heuristics (ELCHs) is proposed for multiple robots, which provides a fast and very accurate solution to loop closing. The proposed framework efficiently compensates the poses of robots in the case of not only rendezvous but also of sharing a common place between the two robots. Two experiments show a significant improvement in pose accuracy by comparing the state-of-the-art map-merging technique and the original ELCH simultaneously.

The problem of reconstruction for a sparse multidimensional signal from a multilinear system with separable dictionaries by a limited amount of measurements is addressed. For this aim, a continuous Gaussian function is used to approximate the l ₀ norm of a tensor signal, and a steepest ascent algorithm is exploited to optimise the cost function. Compared with the conventional reconstruction techniques, which usually convert the multidimensional signal into a one-dimensional (1D) vector, the proposed method can deal with the multidimensional signal directly, and thus it works fast and saves memory usage. Finally, experimental results of hyperspectral imaging demonstrate that the proposed algorithm can well reconstruct the hyperspectral images with a low computational cost.

A novel low-complexity and high-quality colour demosaicking algorithm is proposed for very large-scale integration (VLSI) implementation for real-time video applications. It consists of a boundary detector, a boundary mirror model and five green and red–blue colour interpolation models. Two of the five interpolation models can be selected adaptively according to boundary and position information. In addition, a boundary mirror machine and identical direction technique were used to improve the qualities of the reconstructed images. To reduce the hardware cost, memory requirement and power consumption, a hardware-sharing technique and register bank design were used to realise the proposed algorithm. The VLSI architecture of this work contains only 2.9 K gate counts and its core area is 35 966 μm² synthesised by a 0.18 μm CMOS process. The synthesised results show that this design performs an operating frequency of 100 MHz processing rate by consuming only 1.83 mW. Compared with the previous low-complexity designs, this work not only reduces at least 48.2% of gate counts and 96.7% of power consumption but also improves the average CPSNR quality by more than 0.78 dB.

A novel chrominance just-noticeable-distortion (JND) model based on human colour perception is proposed. The human colour perception based on the density of cones in the retina is quantitatively modelled, and the chrominance JND model using the Gaussian distribution is obtained. To verify its superiority, the chrominance JND model is applied to stereo video coding, which adopts the residual preprocessor to deal with the residuals of stereo videos. Experimental results demonstrate that the proposed chrominance JND model significantly saves bit rate without loss of perceptual quality in stereo videos.

The problem of classifying a remote-sensing image by specifically labelling each pixel in the image is addressed. A novel method, named composite kernels conditional random field (CKCRF), which embeds multiple kernels into a classical CRFs model is proposed. Rather than manually selecting kernel-like KCRF, CKCRFs chooses the appropriate kernel by training. Moreover, a genetic programming-based decision-level fusion framework is proposed to tackle the problem of feature selection. It can select the appropriate features suitable to each category. Evaluations show that CKCRFs outperform CRFs and KCRFs, and CKCRFs with the fusion scheme is better than that without the fusion step.

Taking advantage of the three-dimensional (3D) structure of finger veins located inside a finger, a novel finger vein identification system (FVIS) using two cameras with different fusion techniques is proposed. Compared with the traditional single-camera-based FVIS, the proposed system can generate more discriminative information by fusing information from two simultaneous captured images and can enhance the matching accuracy. Experimental results obtained using the authors' established database containing 436 fingers from 109 subjects verify the feasibility of the proposed system.

The digital micro-mirror device (DMD) and its related techniques have been widely used in various projection equipments. The application of a high-resolution video display scheme based on the DMD is considered. The scheme has been implemented in hardware with a field programmable gate array (FPGA)-based platform, which organises and selects the visual data, and then feeds them into the micro-mirror chip for the projection display based on pulse width modulation (PWM). The proposed scheme divides the video frame into a set of blocks, and the arrays of digital mirrors in different blocks work in a sequential way, so that the needed bandwidth for transferring the image data can be reduced significantly without loss of visual quality.

This Letter studies how to precisely and instantly transform the object images displaying colours on an organic light-emitting diode (OLED) in order to meet both energy saving and personal viewing quality requirements. The proposed method could be applied to a real-time energy saving transformation of any display media on an OLED and it will save display power consumption up to 74% based on the predicted PSNR = 40 dB. At the same time, it still retains a very good image quality after transformation.

A simple and efficient search method based on the coset concept is proposed to construct (3, L) quasi-cyclic low-density parity-check (QC-LDPC) codes without small cycles. Compared with the random search method, the chance to find large-girth codes is remarkably increased for the new method. Compared with Tanner's construction, the proposed method is much more flexible in the selection of row weight L. Some new codes are constructed with the shortest lengths compared with those constructed by the existing well-known methods. Simulation results show that the novel codes with moderate length perform well in the additive white Gaussian noise channel.

Practical implementations of power line communications (PLCs) with multiple-input–multiple-output (MIMO) generally suffer from crosstalk between ports. Presented is a crosstalk ratio (CR)-based adaptive 2 × 2 MIMO PLC along with simulation results that demonstrate an improvement on conventional 2 × 2 MIMO PLC in terms of bit-error-rate.

The sensing matrix is a crucial parameter in the recovery of frequency-sparse signals according to compressive sensing theory. Generally, it is calculated via multiplication of the measurement matrix and the inverse discrete Fourier transform (IDFT) matrix, which involves a large amount of computational work. To reduce the computational load, a fast sensing matrix construction (FSMC) method is developed. The matrices transpose rule, the symmetry property of the discrete Fourier transform (DFT) matrix, the conjugation relation between the DFT matrix and the IDFT matrix are exploited for the first time to develop this FSMC method in which the fast Fourier transform algorithm can be applied. Experiments demonstrate that the FSMC method can boost computational efficiency and contribute to a reduction in computational load without any loss of accuracy.

Bloom filters have found numerous applications in computing and networking systems. They are used to determine whether a given element is present in a set. Counting Bloom filters (CBFs) are an extension of Bloom filters that supports the removal of elements from the set. Traditional Bloom filters require several memory accesses to determine whether an element is present in the set. Recently, fast CBFs that can complete a search operation with only one memory access have been presented. Modern electronic systems are prone to soft errors. These errors can corrupt the contents of memories, causing system failures. In the case of Bloom filters, errors can cause failures where an element that is in the set is classified as not being in the set and the other way around. To avoid those failures, a per-word parity bit is commonly added to detect errors in memories. It is shown that error detection can be implemented in fast CBFs without adding any parity bit. This is achieved by exploiting the properties of the filters to implement error detection.

A power analysis attack countermeasure, called power-awareness-based hiding, is proposed. It is effective in implementing nonlinear operations, S-boxes, in cryptographic algorithms. An advanced encryption standard (AES) S-box circuit has been implemented in this approach using the Domino logic array style. The post-layout simulation results show that the power-aware hiding AES S-box achieves a delay of 1.56 ns and a mean power consumption of 3.57 mW. The proposed method improves the power delay product by 65%, the normalised energy deviation by 43% and the normalised standard deviation by 30% compared to other secure methods.

By minimising the pairwise error probability (PEP) bound subject to the fixed power constraint, a suboptimal precoding scheme for space–time block-coded multiple-input–multiple-output (STBC-MIMO) systems with mean and covariance feedback in spatially correlated Rayleigh fading channels is developed, which can include the mean-feedback only and covariance-feedback only as its special cases. This scheme can achieve performances close to the existing optimal scheme while being more computationally efficient. The simulation results show that the proposed scheme can provide better performances than the conventional equal power scheme, and achieve almost the same performances as the existing optimal scheme.

The selected mapping (SLM) scheme is a competent method for reducing the high peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. One drawback of the conventional SLM (C-SLM) scheme is the high computational complexity. To reduce the complexity of C-SLM, the real and imaginary parts of the OFDM signals are treated separately. The even and odd sequences of the real and imaginary parts are obtained using the Fourier transform properties. More candidates are generated by the different combination of all the sub-sequences. The proposed scheme has a lower computational complexity using only M inverse fast Fourier transform (IFFT) operations to generate M ⁴ candidates. The simulation results show that the proposed scheme achieves good PAPR reduction performance and also reduces the computational complexity significantly compared with the C-SLM scheme.

A three-dimensional (3D) wideband passive harmonic transceiver for long-range embedded wireless monitoring is presented. The wideband performance is achieved by integrating two harmonic repeaters with adjacent centre frequencies. Each repeater consists of a frequency doubler and conjugate-matched receive and transmit meandered monopole antennas. The transceiver operates by receiving a signal at f ₁ between 2.35 and 2.85 GHz and re-radiating a signal at 2*f ₁ and is optimised for low-power operation. The node fits within a λ/8.3 (at 2.4 GHz) diameter sphere and weighs 2.5 g. The transceiver maximum expected efficiency is 5.6% at −18 dBm input power. The transceiver is fabricated via direct print additive manufacturing.

A new kind of leaky wave antenna based on low-frequency surface plasmon polaritons (SPPs) is proposed, which is constructed by periodic metallic blocks with an open slot on the top. Numerical analysis shows that by introducing the open slot on the metallic blocks, there will appear extra spoof SPPs modes in the band gap of metallic solid blocks. The dispersion curve of such spoof SPPs modes passes through the light line and enters into the radiation region, and consequently it can generate a frequency steering pencil-like radiation. Experimental verification agrees with the theory.

An analysis of the influence of three substrate shielding methods, unshielded, patterned-ground shield and floating shield, on a sub-terahertz (sub-THz) inductor is presented. In the sub-THz frequency band, the unshielded inductor showed the best quality-factor (Q-factor) and self-resonance frequency (ƒ_SR) since the inserted substrate shield increases the parasitic capacitance. The simulation results using an electromagnetic simulator showed good agreement with the analysis.

A Doherty power amplifier (DPA) using a novel front-coupled tapered microstrip resonant cell (TMRC) is proposed for linearity and efficiency improvement. The suppression of the second- and higher-order harmonics of the output of the main amplifier is achieved by incorporating the proposed TMRC. Moreover, the compensation of the phase delay and the impedance inversion are performed without any lumped element. The designed power amplifier has been simulated, and measurements of the fabricated power amplifier were made. The third-order inter-modulation distortion of the proposed DPA is reduced by 33 dB compared with the conventional ones.

A new non-dispersive tunable reflection phase shifter is introduced based on the artificial magnetic conductor (AMC) loaded with non-Foster circuits (NFCs). An AMC structure circuit model is extracted and the possibility of mitigating its intrinsic strong dispersion is discussed by loading it with both negative capacitance and negative inductance. The NFC is designed to produce the negative capacitance and inductance based on highly accurate, scalable measurement-based models, and co-simulated with a realistic model of the AMC. The numerical results are in good agreement with the analysis and show a nearly flat reflection phase from 450 to 600 MHz. This flat reflection phase can further be tuned by tuning the loaded inductance from 30 to 50 nH. This investigation paves the way towards a dispersion-less reflection phase shifter design.

The performance improvements for integrated circuit applications of silicon-on-insulator (SOI) metal–oxide semiconductor field-effect transistors (MOSFETs) implemented with diamond layout style (hexagonal gate geometry) are quantified, thanks to the longitudinal corner effect and parallel association of MOSFETs with different channel lengths effect contributions. Futhermore, an accurate analytical drain current model for planar diamond SOI MOSFET for micrometre scale effective channel lengths is proposed and validated. The concept is then extended by 3D simulations for the 150 nm node fully-depleted SOI n-channel MOSFETs.

Switching-contrast enhancement of over 28 dB for all-optical flip-flop (AOFF) operation of a Fabry–Perót semiconductor optical amplifier (SOA) is experimentally demonstrated. Although the two stable flip-flop states of such a device are typically distinguished by their optical power, it is demonstrated that each stable state can also exhibit a unique state of polarisation (SOP). This bistable polarisation rotation (BPR) is leveraged to achieve extreme contrast enhancement by aligning the AOFF reset-state SOP to the blocking axis of a linear polariser, producing a contrast of 36.6 dB. This contrast-enhancement technique is applicable to other AOFFs based on resonant-type SOAs (RT-SOAs) and Kerr-nonlinear media, substantially improving their applicability to advanced photonic-switching applications.

An electro-optic (EO) polarisation conversion type modulator for short-wavelength light using periodically poled MgO:LiNbO₃ is fabricated and the characteristics are evaluated using a tunable GaN laser. High-quality domain-inverted gratings with 3.6 μm were obtained over a 1.0 × 1.0 mm² area. The maximum conversion efficiency, as high as 91%, was obtained. The wavelength bandwidth was 0.7 nm, which was in good agreement with the calculated value, and high wavelength selectivity was obtained.

A novel technique to perform dynamic strain measurement with a Brillouin optical time-domain reflectometry (BOTDR) sensing system based on short-time Fourier transform (STFT) is proposed. Unlike traditional frequency scanning methods, the proposed system samples the Brillouin backscattering signal directly after it has been downconverted to the intermediated frequency (IF) region. The Brillouin frequency shift (BFS) of the sensing fibre was reconstructed from the recorded time-domain data continuously without dead-time, which provided a much higher refreshing rate of the strain measurement. Therefore, dynamic strain variation over an optical fibre can be measured with a single-end structure that is more flexible and reliable. A 16.7 Hz strain variation on a 12 m section was successfully detected at the end of a 270 m sensing fibre with 4 m spatial resolution and 45 με uncertainty.

A family of single-switch SEPIC-derived converters, which apply a tapped inductor (TI), a charge pump (CP) and an inductorless regenerative snubber to attain a high DC step-up at high efficiency is introduced. The proposed converter family has the advantage of continuous input current, which can be helpful in attaining accurate tracking of the maximum power point of solar panels. The feasibility of the proposed topology is verified by simulation and experimental results.

An output-capacitor-less low-dropout regulator (LDR) with an assistant push-pull output stage using a bootstrap technique is proposed. By utilising such a technique, the proposed LDR is able to achieve a fast-transient response. The proposed LDR was implemented in a standard 0.35 μm CMOS process. Measurement results show that the undershoot of the output voltage is 375 mV at the condition of the load current switching from 1 to 200 mA at a rise time of 500 ns.

For the multi-channel in azimuth high-resolution and wide-swath (MC-HRWS) synthetic aperture radar (SAR), a novel maximum-likelihood-based Doppler centroid estimation algorithm is developed. During the estimation process, the Doppler centroid is estimated by using the maximum-likelihood approach to combine the range-frequency-variant Doppler characteristics in each channel, such as the cross-functions between neighbouring channels in the range-frequency domain. In addition, the channel mismatch in phase and along azimuth baseline position measurement error can also be estimated. Finally, the experimental results of some real squint mode MC-HRWS SAR data are utilised to validate the theoretical investigations and the proposed approach.

A suitable emitter structure for the fabrication of InP/InAlGaAs/GaAsSb double heterojunction bipolar transistors (DHBTs) with a passivation ledge is reported. With a composite emitter structure consisting of an InP and thin InAlGaAs, a passivation ledge can be easily fabricated by wet etching. A high current gain of 117 is obtained even for a 0.25 μm emitter DHBT with a base sheet resistance of about 1100 Ω/sq. The fabricated HBT also exhibits an f _max of more than 330 GHz while maintaining a breakdown voltage of more than 9 V.

Motion sensors in smart wristbands/watches have been widely used to sense users’ level of movement and animation. Some studies have further recognised activity contexts using these sensors, such as walking, sitting and running. However, in applications requiring understanding of more complex activities such as interactions with other people or objects, it is necessary to recognise the fine-grained arm action during user interactions with other people or objects. A method to recognise a set of arm actions on a fine-grained level (e.g. checking the wristband, drinking water etc.) is proposed. Motion signals from the accelerometer and gyroscope are transformed into the frequency domain using the short-time Fourier transform. Then, the action patterns are represented by the motion spectrum mixture model and action dynamics are modelled by continuous density hidden Markov models. Tested on a dataset collected from 23 subjects, the method shows satisfying performance and efficiency.

Chaotic multi-dimensional time series (MDTS) exist in some fields such as stock markets and life sciences. To effectively extract the desired information from the measured MDTS, it is important to preprocess data to reduce noise. On the basis of dictionary learning, a method to remove noise is proposed, and the proposed approach is shown to be very effective in the case of MDTS. An MDTS is first considered as a whole, namely an image, and then the method is applied on it. Compared with traditional methods, the proposed approach can utilise the information among the different dimensional time series to improve noise reduction. Using the Lorenz data superimposed by the Gaussian noise as an example, the simulation results have validated the mathematical framework and the performance.

The design and operation of a 9 bit superconductive single-flux-quantum (SFQ) digital-to-analogue converter (DAC) are presented. The DAC comprises a 9 bit variable SFQ pulse number multiplier and a 100-fold voltage multiplier. An SFQ pulse-frequency modulation technique is employed for coding the analogue output voltage. The DAC is fabricated using an Nb Josephson integration technology. Its output voltage waveform, the amplitude of which is up to 2.54 mV _pp, is controlled by digital input signals from a room-temperature data generator.

An appropriate session management technique is crucial in CPE WAN (customer premises equipment code area method) management protocol (CWMP) to efficiently handle numerous sessions. In addition, with the rapid growth of mobile devices, more clients with wireless links result in an environment with possibly higher connection failure rates (CFRs). To improve the resource utilisation in a server cluster, the feature of predictable numbers of connections in all CWMP sessions is used to design a dynamic distribution (DD) technique. By adaptively choosing an appropriate session management strategy, the proposed DD technique helps to minimise memory and time consumption in different network situations. When the network situation is good or there are only a small number of connections, DD distributes each session to a single cluster node. However, as the CFR increases with a large number of connections, DD replicates a session to a number of cluster nodes, but not to all cluster nodes. Furthermore, as the network situation improves, the replicated sessions are adaptively removed so as to reduce memory usage. Experimental results show that the DD approach generally outperforms previous techniques in terms of both memory and time consumption, especially when the CFR is higher than 2.8%.

Cooperative diversity using switched combining, incorporating transmit power control (PC), is investigated for wireless body area networks (BANs). Outage probability and switching rate are derived from extensive empirical measurements, along with savings in circuit power consumption using simple ‘sample-and-hold’ PC in conjunction with switch-and-examine combining (SwC). Theoretical approximation of the switching rate gives a reasonable match with the empirical analysis. It is shown that transmit PC with SwC is an attractive method for increasing network lifetime, through reduced power usage, and for improving radio communications reliability in BANs.

A novel expression for the probability of detection in spectrum-sensing cognitive radio systems is derived over the extended generalised-𝒦 composite fading channel assuming energy detection is employed. The new tractable expression subsumes several fading and shadowing environments as special cases. It can also be easily evaluated using commercial software packages such as MATHEMATICA^© and MATLAB^©.

Several classical goodness of fit (GoF) tests have been used in spectrum sensing. A new GoF test with a unilateral alternative hypothesis for spectrum sensing is proposed. The new test statistic is derived and extended to the case of finite samples. It is shown that the proposed spectrum-sensing method provides improvement in performance and reduction in computational complexity.

For range-free localisation in a wireless sensor network (WSN), the importance of indirect anchor neighbours of an unknown node has been underestimated in the past. In this reported work, for the unknown node, we show that its (n + 1)th-hop anchor neighbours are more useful than its nth-hop ones. By employing a theoretical model to analyse the possible localisation area (PLA) of the unknown node, it is found that the PLA and the hop count are negatively correlated, which indicates that (n + 1)th-hop anchor neighbours can provide more information to more accurately localise the unknown node. Meanwhile, the property of convergence of the theoretical model means that localisation accuracy cannot be unlimitedly improved with increasing hop counts. In the simulations, the presented theory is verified.