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This paper provides a comprehensive performance comparison between a current robust military waveform; namely, MIL-STD-188-110D, Waveform 0, and a filter bank multicarrier spread-spectrum (FBMC-SS) waveform proposed for communications through ionospheric/skywave HF channels. Waveform 0 is effectively a direct sequence spread spectrum waveform that uses Walsh multi-codes to enhance the information transmission rate. It may thus be referred to as Walsh-DSSS. FBMC-SS, on the other hand, makes use of filter banks to provide excellent performance when the received signal is subject to partial band interference. Successful application of FBMC-SS for communications across skywave HF channels has been previously demonstrated, both theoretically and through experimental work. However, very little has been done to contrast FBMC-SS against Walsh-DSSS. The goal of this paper is to first add new features to FBMC-SS to bring it on par with Walsh-DSSS. These features include: (i), introduction of multi-codes that achieve a comparable (or better) data rate to Walsh-DSSS; and (ii), addition of a scrambling step applied to the multi-codes to make the receiver detection robust against widely spread multipaths. With this established, in the second part of the paper, we examine the performance of the developed FBMC-SS against Walsh-DSSS when both are applied for communications across skywave HF channels. The two waveforms are compared both through a theoretical study and through experimental works across several skywave channels ranging from hundreds to thousands of kilometers. [ABSTRACT FROM AUTHOR]

5G systems and networks are expected to provide unprecedented data-rate to final users and services, in combination with increased coverage and density. The traffic generated at the edges of the network should be hauled through high capacity data-conveyors. Extremely high data-rate links able to provide optical-fiber like performance in the order of 100 Gbps are required to reduce the cost and increase the flexibility of the network infrastructure deployment. This paper presents a full transceiver architecture based on a channel-bonding radio-frequency front-end operating at millimeter-wave frequencies and digital baseband processing units able to provide such data-rates with a feasible implementation in low-cost CMOS technologies. The baseband section of the receiver includes digital compensation algorithms that allow to cope with some of the radio front-end impairments. The main functionalities of the proposed transceiver architecture are validated in hardware. [ABSTRACT FROM AUTHOR]

A system for local oscillator (LO) signal generation in 5G millimeter-wave (mmW) multi-antenna transceivers is presented. The system is modular with one phase locked loop (PLL) per antenna element transceiver, and a test circuit implemented in 28-nm fully depleted silicon on insulator (FD-SOI) CMOS features two such PLLs and a 491.52 MHz crystal oscillator (XO) generating a common frequency reference. A fractional-N architecture is employed to achieve high-frequency resolution, and the quantization noise is reduced using a novel frequency divider, which achieves full integer resolution while still using a pre-scaler. The system covers the 3rd Generation Partnership Project (3GPP) bands n257 and n258, achieved by a digital coarse tuning of the voltage-controlled oscillator (VCO). The chip area of each PLL is 0.11 mm2, and 0.029 mm2 for the XO. The total power consumption of the system is 35 mW, where each PLL consumes 15.4 mW and the XO consumes 0.84 mW. The total rms jitter from 20-kHz to 500-MHz offset for a 26-GHz carrier is just 115 fs, corresponding to an FOM $_{\vphantom {R_{j}}j}$ of −244 dB, which is the best reported figure for a fractional-N PLL above 15 GHz. The error-vector magnitude (EVM) due to phase noise is −34.6 dBc using an orthogonal frequency-division multiplexing (OFDM) signal with 120-kHz sub-carrier spacing, sufficient to support 256 QAM. [ABSTRACT FROM AUTHOR]

This paper proposes an active radio frequency (RF) cancellation solution to suppress the transmitter (TX) passband leakage signal in radio transceivers supporting simultaneous transmission and reception. The proposed technique is based on creating an opposite-phase baseband equivalent replica of the TX leakage signal in the transceiver digital front-end through adaptive nonlinear filtering of the known transmit data, to facilitate highly accurate cancellation under a nonlinear power amplifier (PA). The active RF cancellation is then accomplished by employing an auxiliary TX chain to generate the actual RF cancellation signal, and combining it with the received signal at the receiver (RX) low-noise amplifier (LNA) input. A closed-loop parameter learning approach, based on the decorrelation learning rule, is also developed to efficiently estimate the coefficients of the nonlinear cancellation filter in the presence of a nonlinear PA with memory, finite passive isolation, and a nonlinear LNA. The performance of the proposed cancellation technique is evaluated through comprehensive RF measurements adopting commercial LTE-Advanced transceiver hardware components. The results show that the proposed technique can provide an additional suppression of up to 54 dB for the TX passband leakage signal at the LNA input, even at very high transmit power levels and with wide transmission bandwidths. Such a novel cancellation solution can, therefore, substantially improve the TX–RX isolation, hence reducing the requirements on passive isolation and RF component linearity, as well as increasing the efficiency and flexibility of the RF spectrum use in the emerging 5G radio networks. [ABSTRACT FROM PUBLISHER]

A low-power frequency modulated-ultra-wideband (FM-UWB) receiver for short-range communications, capable of simultaneously demodulating multiple FM-UWB signals located at the same frequency, is presented in this paper. The proposed receiver utilizes an “approximate zero IF” architecture that uses a low-power, free-running ring oscillator as the RF LO to first convert the input signal into baseband, where it is then amplified and demodulated. Moving the most power-hungry blocks from RF to IF results in reduction of power consumption by more than one order of magnitude compared to previous implementations using the delay-line demodulator. Integrated in a 65-nm CMOS technology, the whole receiver chain consumes 423 \mu \textW from a 1-V supply while achieving −70-dBm sensitivity at a data rate of 100 kb/s at 4 GHz. Communication with up to four FM-UWB users, operating in the same band, is demonstrated, making this receiver suitable for high-density wireless sensor networks. [ABSTRACT FROM AUTHOR]

A fully integrated 802.11ad/WiGig compliant 60 GHz transceiver is presented in a 130 nm SiGe BiCMOS technology. Encompassing an area of 2.3 mm\, \times \,2.16 mm = 4.97 mm^2, the transceiver covers the entire 60 GHz band, from 57 to 66 GHz. Within this span, the RX NF, TX OP1dB, and PLL RMS jitter is better than 5.5 dB, + 13.5 dBm, and 7^\circ, respectively. The transceiver is packaged in 1) a system-in-package substrate with industry standard WR-15 transition providing an approximate 1 dB insertion loss, and 2) a cost-effective 7\, \times \,7 mm^2 organic BGA package with integrated transmit and receive antennas providing 8 dBi gain. In system-level testing, the transceiver is fully compliant with all TX EVM and RX sensitivity requirements of the WiGig standard up to the top-rate 16-QAM operating mode and across all standard channel frequencies. Link testing over the air with the antenna-integrated package shows a range of 5.9 m at 4.6 Gbps and over 20 m at 2.5 Gbps. This system achieves the highest performance 802.11ad/WiGig compliant wireless links of any reported single-element transceiver. [ABSTRACT FROM PUBLISHER]

This paper presents the first truly wireless 24-GHz round-trip time-of-flight local positioning frontend with an integrated CMOS transceiver. The transceiver in 130-nm CMOS technology features a novel receiver/transceiver switching concept, which reduces RF losses between the receiver/transmitter and antenna and drastically improves the transmit/receive isolation. The low-power RF transceiver chip was integrated with a digital signal-processing unit and mounted on a circuit board to form a system-level demonstrator of a secondary radar node incorporating synchronization and a distributed localization algorithm. The performance of the self-organizing localization network is evaluated in an indoor setup using comparisons with reference trajectories. Experimental results show a distance precision between the active nodes close to the theoretical optimum that can be achieved with the used signal parameters, as well as an absolute localization error in the centimeter range. [ABSTRACT FROM AUTHOR]

We study the robust transceiver design for amplify-and-forward (AF) multiple-input-multiple-output (MIMO) relay systems with a direct link and imperfect channel state information (CSI). Under this circumstance, we aim at obtaining the globally optimal transceiver that minimizes the mean-squared error (MSE) of symbol detection. Specifically, given a source beamformer, we first derive closed-form expressions for the optimal relay precoder and destination receiver. Then, to tackle the intricate non-convex problem with respect to source beamformer, we develop an efficient approach involving one-dimensional search and semidefinite programming (SDP). We prove rigourously that the proposed method yields a globally optimal solution. Simulation results verify the pronounced performance provided by the proposed design. [ABSTRACT FROM AUTHOR]

Radio technology for future broadband wireless applications presents a remarkable research opportunity for the RF transceiver and circuit design community. A survey is presented of the low-noise amplifier, frequency conversion, filtering, and transmitter techniques that are being explored for future wireless devices that require wide tuning range, flexible modulation formats, low dc power, and low cost. In all cases, the traditional disadvantages of broadband design approaches can be mitigated by taking advantage of higher levels of integration afforded by CMOS and BiCMOS technologies and improved circuit design approaches. [ABSTRACT FROM AUTHOR]

This paper describes a 4.48 GHz-5.89 GHz LC voltage-controlled oscillator (LC-VCO) as a key component in RF transceivers. The circuit is fully designed in TSMC's 65 nm radio-frequency complimentary metal-oxide-semiconductor technology process. The LC-VCO uses the structure of only one couple of NMOS differential negative resistances, tank circuit which consists of an optimal on-chip spiral inductor with switched capacitor and varactor arrays. The proposed design accomplishes wide tuning range frequency by using 6-bit switch capacitor array in addition to linearly varying MOS varactors. A switched current source block is used to improve the performance of the LC-VCO. The oscillator has a wide tuning range, between 4.48 GHz and 5.89 GHz. The LC-VCO dissipates 15.96 mW from a voltage supply of 1.8 V, whereas its phase noise is -124.1 dBc/Hz at 1 MHz offset of a at 5.89 GHz carrier. [ABSTRACT FROM AUTHOR]

This paper presents a fully-integrated IR-UWB radio, designed to operate within the limits of mm-scale micro-battery for cubic-mm sensor nodes. It includes an RF front-end, battery current limiter, baseband modem with I2C interface, and temperature-compensated relaxation oscillator for frequency generation without a crystal. The peak current draw from a modern mm-scale battery must be <100 µA, below a radio's active power consumption. Thus, duty-cycling the radio only at the packet level is not an option, and so this IR-UWB radio includes an integrated modem which duty-cycles the RF front-end at the bit-level. A current limiter protects the battery from over-current conditions, and the radio operates from on-chip storage capacitance that is recharged between bits. The radio operates at 30 kb/s with a center frequency of 9.8 GHz. It consumes 291 µW average power in transmit mode while broadcasting 0.1 dBm pulses, and 306 µW in receive mode with a sensitivity of –77 dBm. The area of the radio is 2.73 mm². [ABSTRACT FROM PUBLISHER]

Accurately determining the position of radio receivers can aid in the rapid discovery of radio-controlled explosives. Prior research has demonstrated that superheterodyne receivers unintentionally emit low-power radio signals during normal operation. By using a weak stimulation signal, it is possible to inject a known signal into these unintended emissions. This process is known as stimulated emissions. In this paper, a method is developed using radarlike techniques to determine the range to the radio receiver. Unlike conventional radar, it depends on the modification of the unintended emissions from the device and not on a passive reflection. High-bandwidth stimulated emissions measured from a typical superheterodyne receiver—which was not designed to be located—are used to make high-resolution time-of-arrival measurements. A continuous-wave radarlike system was designed, and its hardware realization is discussed. The accuracy of the radar is tested in a noisy multipath-rich indoor environment. Results indicate that the proposed radar can locate superheterodyne radio receivers that are 50 m away or more. The root-mean-square position error is less than 5 m when the signal-to-noise ratio is 15 dB or above. The proposed system offers a viable alternative to existing techniques for locating radio-controlled explosives. [ABSTRACT FROM PUBLISHER]

This paper describes the design and realization of a 5.6-GHz ultrawide-bandwidth-based position measurement system. The system was entirely made using off-the-shelf components and achieves centimeter-level accuracy in an indoor environment. It is based on asynchronous modulated pulse round-trip time measurements. Both system level and realization details are described along with experimental results including estimates of measurement uncertainties. [ABSTRACT FROM PUBLISHER]

A scheme for cheaply, easily, and accurately measuring the gains and radiation patterns of Wi-Fi-band antennas is presented. Considering the cost, size, and convenience, a high-gain microstrip Vivaldi antenna, based on anisotropic zero-index metamaterials, is used for the transmitter. A homodyne receiver is designed to simplify the receiver's architecture. Implementing an RF switch and a dual-polarized antenna, the design is also suitable for testing non-standard-polarization antennas. The proposed measurement system has been validated by comparing the results to a commercial measurement system. [ABSTRACT FROM AUTHOR]

We study and compare the performance of two bidirectional network beamforming schemes, namely the multiple access broadcast channel (MABC) strategy and the time division broadcast channel (TDBC) protocol, using joint optimal power control and beamforming design. To do so, we first design two TDBC-based bidirectional network beamformers, through minimization of the total power consumed in the whole network subject to quality of service (QoS) constraints, for the two cases with and without a direct link between the two transceivers. The corresponding power minimization problems are carried out over the transceiver transmit powers as well as relay beamforming weights, thus resulting in a jointly optimal power allocation and beamforming criterion. We devise optimal second-order cone programming based solutions as well as fast gradient-based solutions to these problems. We then use these solutions to compare the performance of the underlying TDBC-based approach to that of the MABC-based technique. This comparison is important because the TDBC approach appears to have certain advantages which can be exploited towards improving the performance of two-way network beamforming. These advantages include the additional degrees of freedom as well as the possibility of benefitting from the availability of a direct link between the two transceivers. Interestingly, in the absence of a direct link between the two transceivers, we show that when the QoS constraints are imposed to meet certain given probabilities of uncoded error [or, equivalently, to meet certain signal-to-noise ratio (SNR) constraints], these two schemes perform closely in terms of the minimum total transmit power. However, when the QoS constraints are used to guarantee certain given rates, the MABC-based scheme outperforms the TDBC counterpart. In the case when a direct link exists between the two transceivers, the TDBC-based approach can outperform the MABC-based method, even for rate satisfying QoS constraints, provided that the direct link is strong enough. [ABSTRACT FROM PUBLISHER]

Due to its simple structure and reduced requirements for radio frequency filtering, the direct-conversion principle has recently gained a lot of interest in radio transceiver design. This paper considers the so-called inphase/quadrature (IJQ) imbalance problem in such structures under the assumption of frequency. selective transmission channel requiring equalization on the receiver side. It will be shown that IJQ imbalance and channel equalization are strongly interdependent, and thus, IJQ mismatch should be taken into account in the equalizer design, and vice versa, particularly with high-order symbol alphabets. Most importantly, the amount of signal distortion caused by transmitter and receiver IJQ imbalances to the equalized received signal will be analytically analyzed through signal-to-interference ratio (SIR) analysis. This gives a quantitative measure to analyze and judge the role of IJQ imbalances in practical communication system design, without having to resort to lengthy data simulations. Furthermore, the analysis shows that imbalance levels that are tolerable in additive white Gaussian noise channels can turn into a serious problem in multipath channels requiring equalization. This gives further motivation and invaluable insight in the overall receiver and system design and in developing digital signal processing-based techniques to mitigate the L/Q imbalance effects on the receiver side. In general, the analytical outcomes and results are verified using extensive computer simulations. [ABSTRACT FROM AUTHOR]

An active filtering technique to remove the out-of- band blockers in wireless receivers is presented. The circuit employs a feed-forward filtering path to produce an arbitrarily narrow frequency response in the low-noise amplifier (LNA), eliminating the need for an external surface acoustic wave (SAW) filter at the receiver front-end. The required notch filtering in the feed-forward path is realized through a receiver translational loop, driven by the same local oscillator (LO) signals used in the main receiver. For the proof of concept, a prototype amplifier in 65 nm standard CMOS, intended for Global System for Mobile Communication (GSM) applications, is implemented. When the filtering is enabled, the amplifier 3-dB bandwidth reduces from 220 MHz to about 4.5 MHz, and a stop-band rejection of over 21 dB is achieved. [ABSTRACT FROM AUTHOR]

A single-chip 2.4-GHz CMOS radio transceiver with integrated baseband processing according to the IEEE 802.15.4 standard is presented. The transceiver consumes 14.7 mA in receive mode and 15.7 mA in transmit mode. The receiver uses a low-IF topology for high sensitivity and low power consumption, and achieves -101 dBm sensitivity for 1% packet error rate. The transmitter topology is based on a PLL direct-modulation scheme. Optimizations of architecture and circuit design level in order to reduce the transceiver power consumption are described. Special attention is paid to the RF front-end design which consumes 2.4 mA in receive mode and features bidirectional RF pins. The 5.77 mm² chip is implemented in a standard 0.18-µm CMOS technology. The transmitter delivers +3 dBm into the 100-Ω differential antenna port. [ABSTRACT FROM AUTHOR]

A fully integrated dual-mode CMOS transceiver tuned to 2.4 GHz consumes 65 mA in receive mode and 78 mA in transmit mode from a 3-V supply. The radio includes all the receive and transmit building blocks, such as frequency synthesizer, voltage-controlled oscillator (VCO), and power amplifier, and is intended for use in 802.11b and Bluetooth applications. The Bluetooth receiver uses a low-IF architecture for higher level of integration and lower power consumption, while the 802.11b receiver is direct conversion. The receiver achieves a typical sensitivity of -88 dBm at 11 Mb/s for 802.11b, and -83 dBm for Bluetooth mode. The receiver minimum IIP3 is -8 dBm. Both transmitters use a direct-conversion architecture, and deliver a nominal output power of 0 dBm, with a power range of 20 dB in 2-dB steps. [ABSTRACT FROM AUTHOR]