Non-coherent Energy Detection Research Articles

A Detection Scheme for Integrated SWIPT Receivers With Rectenna Arrays

Smart devices and their applications led to a rapid evolution of the Internet of Things. As a result, there is an emerging need on energizing those low-power devices, while at the same time achieving information transfer. In this context, simultaneous wireless information and power transfer (SWIPT) is considered as an appealing technology, since it can power wirelessly and remotely such devices, simultaneously with information transfer. Motivated by this, we herein propose a system model with an integrated SWIPT receiver, succeeding enhanced performance in terms of information decoding (ID) and energy harvested (EH). Specifically, we adopt a single input multiple output topology, where at the receiver’s side we examine two antenna architectures, one based on the direct-current (DC) combining and the other on the radio-frequency (RF) combining. For both schemes, we consider multiple receive antennas and rectifiers, comparing their performances. Furthermore, we adopt a piece-wise linear EH model, which takes into account the sensitivity and saturation effects of the rectifiers. By using a maximum likelihood-based soft decoding, a non-coherent energy detection is achieved. Finally, an asymptotic analysis is conducted, providing upper and lower bounds for ID and EH, respectively. Simulation results along with theoretical analysis, validate the enhanced performance both in terms of ID and EH.

Multi-level pulse position modulation scheme for enhancing link capacity in electromagnetic nanocommunication networks

In this letter, a new nanocommunication modulation scheme termed multi-level pulse position modulation (ML-PPM) is proposed. The ML-PPM approach will boost the link capacity of a nanocommunication system while achieving a processing gain in reception. The bit error rate and link capacity of the scheme are evaluated using a non-coherent energy detection nanoreceiver. Simulation results show that the proposed scheme has a substantially greater link capacity than the existing schemes including time-spread on–off keying (TS-OOK) and M -ary pulse position modulation (PPM).

Channel Capacity of an Asymmetric Constellation in Rayleigh Fading With Noncoherent Energy Detection

The channel capacity of noncoherent reception of multi-level one-sided amplitude-shift keying (ASK), which is an asymmetric constellation, in Rayleigh fading with receive diversity and energy detection is considered. The asymmetries result in capacity achieving input probability distributions, that is, a priori probability distributions, that deviate from uniformity. An analytical expression for the mutual information in terms of a single integral is derived, and from it the set of equations, which can be solved to obtain the optimum or capacity achieving input probabilities, is obtained. High and low signal-to-noise ratio (SNR) approximations of the optimum input probabilities and the capacity are derived next. Furthermore, a logarithmic upper bound on the mutual information is obtained. Numerical results confirm that the uniform distribution of input probabilities is not capacity achieving. For example, with average SNR per symbol per branch of 6 dB, the relative deviation of the mutual information (with uniform input distribution) from the capacity is nearly 20% for 4-level ASK with one transmit diversity branch and two receive diversity branches. Furthermore, the derived high and low SNR approximations to the capacity are shown to be reasonably accurate.

A Digitally Controlled Multichannel Spectrally Efficient Low-Power Transceiver for Ultra-Wideband Cognitive Radio Applications

A multichannel transceiver design with low hardware complexity, flexibility and efficient spectrum use intended for Impulse Radio (IR) Ultra-Wideband (UWB) apertures, is proposed in this paper. The transceiver supports 14 channels and is implemented in TSMC CMOS process. The transmitter adopts a symmetrical triangular narrow pulse generator, a multiband LC-VCO, a mixer and a Variable-Gain Amplifier. A digital control of transmitter output power and carrier frequency is achieved by a current-steering Digital-to-Analog Converter (CS-DAC). The receiver follows the noncoherent Energy Detection (ED) scheme including Low-Noise Amplifier (LNA) which takes the benefits of the body biasing technique to further reduce power consumption, squarer and comparator. The LNA achieves high gain of up to 30[Formula: see text]dB allowing to enhance the receiver sensitivity which is [Formula: see text]83.7[Formula: see text]dBm at 25[Formula: see text]Mbps. The transmitter provides output pulses with a width of 3[Formula: see text]ns, a pulse repetition rate of 20[Formula: see text]ns and a maximum Power Spectral Density (PSD) of [Formula: see text]42[Formula: see text]dBm/MHz. The power consumptions of transmitter and receiver are 35.6[Formula: see text]pJ/bit and 0.207[Formula: see text]nJ/bit at 25[Formula: see text]Mbps, respectively. Maximizing utilization of the scarce wireless spectrum, enhancing spectral flexibility and efficiency and reducing power consumption are the main contributions brought by this work, enabling this transceiver to be able to deal with the current debate on producing single multifunctional Cognitive Radio (CR) UWB systems.

A 6.5–8.1-GHz Communication/Ranging VWB Transceiver for Secure Wireless Connectivity With Enhanced Bandwidth Efficiency and $\Delta\Sigma$ Energy Detection

This article describes a pulse-based transceiver architecture for mobile authentication with location verification. A time-of-flight (TOF) measurement method is employed as a physical layer countermeasure against relay attack. For bandwidth-efficient pulse transmission with enhanced link margin, frequency-hopping very-wideband (VWB) pulse generation is used. A noncoherent energy detection receiver is designed for TOF-based ranging to have demodulation with low power and low latency. The position of an energy integration window is automatically tracked for both pulse-position modulation (PPM) synchronization and coarse ranging. A $\Delta \Sigma $ energy detection method is proposed to convert ranging information to a 1-bit digital output without requiring asynchronous edge detection (ED). A prototype 6.5–8. 1-GHz VWB transceiver is implemented in 65-nm CMOS. Three channels are realized by having a channel bandwidth of about 400 MHz with a tunable guard band between two adjacent channels. The transceiver achieves the ranging accuracy of 2.0 cm and the demodulation latency of 20 ns, consuming 6.0 mW with a sensitivity of −69 dBm at 5 Mb/s.

Noncoherent Backscatter Communications Over Ambient OFDM Signals

In recent years, ambient backscatter communications have gained a lot of interests as a promising enabling technology for the Internet-of-Things and green communications. In ambient backscatter communication systems, ultra-low power devices are able to transmit information by backscattering ambient radio-frequency signals generated by legacy communication systems such as Wi-Fi and cellular networks. This paper is concerned with ambient backscatter communications over legacy orthogonal frequency division multiplexing (OFDM) signals. We propose a backscatter modulation scheme that allows backscattering devices to take advantage of the spectrum structure of ambient OFDM symbols to transmit information. The proposed modulation scheme allows both binary and higher-order modulation using noncoherent energy detection. We investigate the detector design and analyze the error performance of the proposed scheme. We provide an exact expression for the error probability for the binary case, whereas accurate approximate expressions for the error probability are derived for the $M$ -ary case. We corroborate our analysis using Monte–Carlo simulation and investigate the effects of varying the OFDM symbol size, maximum channel delay spread, and the number of receive antennas on the error performance. Our numerical results show that the proposed technique outperforms other techniques available in this paper for backscatter communication over ambient OFDM signals in different scenarios.

Rational-Orthogonal-Wavelet-Based Active Sonar Pulse and Detector Design

A family of rational orthogonal wavelets is explored in active sonar detection to achieve Doppler robustness and noise mitigation. The broadband active sonar system is classified as wavelet-based noncoherent subband energy detection. It features a flexible broadband sonar pulse design with low peak-to-average power ratio (PAPR), and a detector of low computation complexity via fast rational wavelet filter bank. The designed family of broadband pulses is based on a combination of multiple basis functions of the complex rational orthogonal wavelet (CROW). Differing from the conventional dyadic wavelet (with an integer scale factor of 2), the CROW has a rational scale factor and much higher resolution in the partition of the time-scale plane. This family of wavelets presents great flexibility in the system design. Design example is presented with minimized PAPR to serve for applications demanding the stealth. The sonar detector is based on the CROW analysis filter bank. Detection performance is analyzed regarding its resistance to Doppler noise and multipath by simulations using a geometric underwater acoustic channel model. The performance of the wavelet-based active sonar system is compared with a linear frequency modulated pulse-based system. The receiver operating characteristic curves demonstrate that the designed system is able to cope with severe multipath, high ambient noise, and severe Doppler dispersion. The framework provides possible solutions for underwater applications in low signal-to-noise ratio and varying mobility conditions.

Efficient Hybrid Modulation/Demodulation Scheme Using Differential Encoding/Decoding for UWB-IR

An efficient hybrid modulation/demodulation scheme using a short duration pulse in the time-domain for ultra wideband-impulse radio (UWB-IR) systems is proposed. The proposed modulation scheme is pulse position modulation (PPM) of the UWB-IR standard modulation combined with differential encoding, and non-coherent energy detection (ED) adopting differential decoding is proposed for demodulation. Differential encoding makes a pulse that can transfer additive information bit into bits assigned in one symbol without increasing the symbol period. The BER performance is evaluated for 2-PPM, 4-PPM and the proposed HD-2PPM (which has the same symbol duration as BPPM and includes two information bits per symbol). The error performance indicates that the proposed scheme is an outstanding 0.5 dB over existing schemes of UWB-IR, and the data-rate performance shows that the proposed method has higher spectral efficiency than conventional methods that occupy the same duration as the proposed scheme.

Modeling and Identification of Ultra-Wideband Analog Multipliers

Analog multipliers are employed in many applications. In conventional RF front ends, for example, they are widely used for frequency conversion tasks. In noncoherent energy detectors or autocorrelation receivers, they multiply the (broadband) input signal by itself to achieve a down-conversion. Unfortunately, there exist no ideal hardware realizations of such devices, hence multipliers inevitably create undesired signal content at their output. To be able to deal with these effects or correct for them, we need to be able to model and identify realistic RF multipliers. This paper proposes and validates a multiple-input single-output Wiener–Hammerstein model for ultra-wideband (UWB) analog multipliers. The structure of the proposed model gives insight in the distortions created. It thus provides the possibility to study the realistic behavior of systems involving those multipliers, e.g., the influence of undesired nonlinear signal content onto noncoherent UWB receivers. A comparison of the model performance is shown with respect to measurements and circuit simulations.

Threshold selection method for UWB TOA estimation based on wavelet decomposition and kurtosis analysis

In wireless sensor networks, ranging or positioning via ultra-wideband (UWB) has caused widespread research interests where the non-coherent energy detection (ED) method with low sampling rate and low complexity is widely studied. However, the traditional energy detection methods only analyze the signal energy in the time domain, so their error is relatively large. In this paper, the simulation results show that most of the signal energy concentrates in the low-frequency band, so a novel threshold selection method for time of arrival (TOA) estimation is proposed that analyzes the signals in both time domain and frequency domain. In this method, the received signal is decomposed by “db6” wavelet and the kurtosis of energy blocks of the low-frequency wavelet coefficients (Kc) is analyzed. At last, the mapping relationship between Kc and the normalized threshold for TOA estimation is created using polynomial fitting with degree 3. The simulation results show that the TOA estimation error of the proposed method is significantly less than the method without wavelet decomposition.

An UWB ranging method based on wavelet packet decomposition

In wireless sensor networks (WSNs), precise ranging or positioning using Ultra-Wideband (UWB) signal attracts a wide research interest. The advantages of non-coherent energy detection (ED) are low sampling rate and low complexity, but the traditional energy detection schemes only analyze UWB signal in time domain, so the ranging or positioning error is large. In this paper, a novel ranging method is proposed which analyzes UWB signal in joint time-frequency domain. In this method, wavelet packet decomposition (WPD) is used to get the energy distributions in different sub-bands, and then back propagation artificial neural network (BP-ANN) is utilized to establish the mapping relationship between energy distributions and transmission ranges. The simulation results show that the ranging error of the trained BP-ANN in this method is significantly less than the traditional ED methods.

A Locally Optimal Soft Linear-Quadratic Scheme for CR Systems in Shadowing Environments

In this letter, we analyze the problem of detecting spectrum holes in cognitive radio systems under the Neyman–Pearson scenario. We consider that a group of unlicensed users use noncoherent energy detectors to sense the radio signal and design a soft locally optimal linear-quadratic statistic based on the deflection coefficient. Each unlicensed user transmits the processed data to a central entity, where the decision about the presence or not of licensed users is made. Using the method of Monte Carlo, we show that the proposed statistic outperforms previous ones available in the literature in a wide range of shadow-fading scenarios and it is robust against parameters errors.

0.18㎛ CMOS 공정을 이용한 WBAN용 비동기식 IR-UWB RF 송수신기

In this paper, an Impulse Radio-Ultra Wide band RF Transceiver for WBAN applications is implemented in CMOS technology. The designed RF transceiver support 3-5GHz UWB low band and employs OOK(On-Off Keying) modulation. The receiver employs non-coherent energy detection architecture to reduce complexity and power consumption. For the rejection of the undesired interferers and improvement of the receiver sensitivity, RF active notch filter is integrated. The VCO based transmitter employs the switch mechanism. As adapt the switch mechanism, power consumption and VCO leakage can be reduced. Also, the spectrum mask is always same at each center frequency. The measured sensitivity of the receiver is -84.1 dBm at 3.5 GHz with 1.579 Mbps. The power consumption of the transmitter and receiver are 0.3nJ/bit and 41 mW respectively.

Low-power, low-rate ultrasonic communications system transmitting axially along a cylindrical pipe using transverse waves.

Acoustic-electric channels have been used in the recent past to send power and data through thin metallic barriers. Acoustic-electric channels formed along a structure which are highly attenuative and nonreverberant could have potential applications in aerospace, nuclear, and oil industries, among others. This work considers data transmission along the length of a cylindrical pipe both when in air and when filled and immersed in water using shear waves of transverse polarity. To combat the effects of frequency selectivity and to address the available power constraints, a simple modulation scheme using noncoherent demodulation is employed for data transmission: chirp-on-off keying (Chirp-OOK). The wideband nature of the chirp waveform provides resilience against nulls in the channel response while making it possible to implement a simple noncoherent energy detector. Monte Carlo simulation results using measured channel responses suggest that the bit error rate performance of the scheme matches quite closely with the theoretical results. The energy detector performance is independent of the type of the channel used as long as intersymbol-interference is negligible and same received Eb/N0 is maintained. A low-power prototype hardware system was implemented using microcontrollers, commercial ICs, and custom circuits. Successful data transmission was achieved across the 4.8 m length of pipe (in air and water) for a data rate of 100 bps using approximately 5 mW of transmit power.

Optimal Energy Efficiency Link Adaptation in IEEE 802.15.6 IR-UWB Body Area Networks

We propose a novel link adaptation mechanism to maximize energy efficiency in IEEE 802.15.6 impulse radio ultra wideband (IR-UWB) wireless body area networks (WBANs). We consider noncoherent energy detection and autocorrelation receivers, suitable for low complexity implementations. The amount of captured energy is first modeled for the on-body WBAN channel. Using our energy capture model and Gaussian approximations for the decision statistic, the error performance of various physical layer modes of the IEEE 802.15.6 standard is derived assuming intra-symbol interference. We refer to the IEEE 802.15.6 specification as a use case. The proposed adaptation scheme can be applied to any other IR-UWB system with noncoherent receivers and is based on the estimated signal to noise ratio and the channel's energy capture index for which we propose unbiased estimators.

A cross-layer energy efficiency optimization model for WBAN using IR-UWB transceivers

An energy efficiency optimization model for the IEEE 802.15.6 standard based wireless body area network is described in this paper. Cross-layer approach has been used here by focusing on physical (PHY) and medium access control (MAC) layers taking into account relevant characteristics therein. Studied PHY is based on impulse radio ultra wideband (IR-UWB) signaling with mandatory on---off keying modulation and non-coherent energy detection receiver. The analyzed MAC protocol is slotted Aloha which is used in the contention based mode of the IEEE 802.15.6 std. using IR-UWB PHY. The proposed model can be used to compare the energy efficiency of uncoded and coded transmissions using different Bose---Chaudhuri---Hocquenghem code rates. The model enables joint code rate and packet length optimization in AWGN channel when using the path loss model for hospital scenario, defined by the IEEE P802.15 working group. Results clearly show the most energy efficient code rate and packet length as a function of distance.

A Cross-Layer Optimization Approach for Lower Layers of the Protocol Stack in Sensor Networks

A cross-layer optimization approach for the physical and medium access control layers of wireless sensor networks is introduced in this article. This approach includes a Markov chain model, simulations, and analytical derivations that are applied to the analysis of sensor networks using impulse radio ultra-wideband signals with noncoherent energy detection. This type of communication system has low-power transmission requirements and noise like signal characteristics with low interference to other wireless systems. The energy efficiency of different Reed-Solomon code rates and uncoded case are studied in a star topology network, where slotted Aloha, as defined in the IEEE 802.15.4a standard, is used as the medium access protocol. Analytical and simulation results clearly show the potential energy gains that can be achieved with the proposed optimization approach that can be also used in the evaluation and optimization of other combinations of physical and medium access control protocols.

Performance Analysis of Time Reversal UWB Communication with Non-coherent Energy Detector

Non-coherent receivers, such as energy detectors (ED), are the simplest and the most practical alternatives to coherent receivers for low-rate and low-complexity applications in ultra-wideband (UWB) systems. However, these advantages are achieved at the expense of non-negligible performance degradation. One solution to improve the performance is to make use of time reversal (TR) technique. In this study, the performance of TR technique with non-coherent ED is analyzed in UWB systems. First, we derive an approximate analytical formula for the error probability of TR-ED which is based on tapped-delay line (TDL) channel model. Next, we theoretically and by simulations analyze the optimum integration interval which maximizes the performance of TR-ED. The results show that TR technique, by reducing the integration interval, considerably improves the performance compared to the conventional ED scheme.

A Crystal-Less Self-Synchronized Bit-Level Duty-Cycled IR-UWB Transceiver System

A self-synchronized dual-band OOK IR-UWB transceiver system for short-range, low-data rate sensor networks is demonstrated. The transceiver system utilizes asynchronous non-coherent energy detection coupled with a novel pulse-coupled injection-locking scheme to synchronize transceivers throughout the network at nanosecond-scale precision. The pulse-coupled synchronization scheme compensates for intrinsic frequency variation so that all timing in the system can be derived from an integrated relaxation oscillator operating at a nominal frequency of 150 KHz. A low-jitter PLL and simple combinational logic is used for timing generation and control. The system is duty cycled between the expected arrival times of the sync and data pulses, allowing a demonstrated average RF duty cycle of less than 1% while being able to maintain synchronization for nearly 1 million cycles. Total measured system power consumption is 119 μW while actively communicating with 1200 bit packets. The transceiver was designed in a 90 nm IBM CMOS process and occupies 1.7 mm2 of active area.

A 20-Mb/s Pulse Harmonic Modulation Transceiver for Wideband Near-Field Data Transmission

This brief presents a fully integrated low-power transceiver for wideband near-field data transmission across inductive telemetry links based on pulse harmonic modulation (PHM). This PHM transceiver uses two narrow pulses with specific amplitudes and timing at the transmitter (Tx) to suppress intersymbol interference (ISI) at the receiver (Rx) high-Q LC tank to achieve high data rates (DRs) without reducing the inductive link quality factor to extend its bandwidth. This method significantly improves the range and selectivity of the link. The PHM Rx architecture is based on noncoherent energy detection utilizing a novel pulse-based automatic gain control circuit, which significantly reduces the power consumption (46%) and ISI at short coupling distances. The PHM transceiver was fabricated in a 0.35- μm standard CMOS process and achieved a measured DR of 20 Mb/s with a bit error rate of 8.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> at a 10-mm distance using planar figure-8 coils. The PHM Tx and Rx power consumptions were 180 and 12.15 pJ/bit, respectively, at a 1.8-V supply voltage.