Radio over fibre distribution systems for ultra-wide band and millimetre wave applications

Short range wireless technology such as ultra-wideband (UWB) and 60 GHz millimetre wave (mm-wave) play a key role for wireless connectivity in indoor home, office environment or large enclosed public areas. UWB has been allocated at the frequency band 3.1-10.6 GHz with an emission power below -41.3 dBm. Mm-wave signals around 60 GHz have also attracted much attention to support high-speed data for short range wireless applications. The wide bandwidth and high allowable transmit power at 60 GHz enable multi-Gbps wireless transmission over typical indoor distances. Radio-over-fibre (RoF) systems are used to extend the propagation distance of both UWB and mm-wave signals over hundred of meters inside a building. UWB or mm-wave signals over fibre can be generated first at the central office before being distributed to the remote access points through optical fibre. In this work, we investigate two new techniques to generate and distribute UWB signals. These techniques are based on generating Gaussian pulse position modulation (PPM) using a gain switched laser (GSL). The simulation and experimental results have been carried out to show the suitability of employing gain switching in UWB over fibre systems (UWBoF) to develop a reliable, simple, and low cost technique for distributing UWB pulses. The second part of this work proposes two configurations for optical mm-wave generation and transmission of 3 Gbps downstream data based on GSL. We investigate the distribution of these two methods over fibre with wireless link, and demonstrate the system simplicity and cost efficiency for mm-wave over fibre systems. Both configurations are simulated to verify our obtained results and show system performance at higher bit rates. In the third part, we generate phase modulated mm-waves by using an external injection of a modulated light source into GSL. The performance of this system is experimentally investigated and simulated for different fiber links

Ultra-wideband indoor communications using optical technology

La communication ultra large bande (UWB) a attiré une énorme quantité de recherches ces dernières années, surtout après la présentation du masque spectral de US Federal Communications Commission (FCC). Les impulsions ultra-courtes permettent de très hauts débits de faible puissance tout en éliminant les interférences avec les systèmes existants à bande étroite. La faible puissance, cependant, limite la portée de propagation des radios UWB à quelques mètres pour la transmission sans fil à l’intérieur d’une pièce. En outre, des signaux UWB reçu sont étendus dans le temps en raison de la propagation par trajet multiple qui résulte en beaucoup d’interférence inter-symbole (ISI) à haut débit. Le monocycle Gaussien, l’impulsion la plus commune dans UWB, a une mauvaise couverture sous le masque de la FCC. Dans cette thèse, nous démontrons des transmet- teurs qui sont capables de générer des impulsions UWB avec une efficacité de puissance élevée. Une impulsion efficace résulte dans un rapport de signal à bruit (SNR) supérieur au récepteur en utilisant plus de la puissance disponible sous le masque spectral de la FCC. On produit les impulsions dans le domaine optique et utilise la fibre optique pour les transporter sur plusieurs kilomètres pour la distribution dans un réseau optique pas- sif. La fibre optique est très fiable pour le transport des signaux radio avec une faible consommation de puissance. On utilise les éléments simples comme un modulateur Mach-Zehnder ou un résonateur en anneau pour générer des impulsions, ce qui permet l’intégration dans le silicium. Compatible avec la technologie CMOS, la photonique sur silicium a un potentiel énorme pour abaisser le coût et l’encombrement des systèmes optiques. La photodétection convertit les impulsions optiques en impulsions électriques avant la transmission sur l’antenne du côté de l’utilisateur. La réponse fréquentielle de l’antenne déforme la forme d’onde de l’impulsion UWB. Nous proposons une technique d’optimisation non-linéaire qui prend en compte la distorsion d’antenne pour trouver des impulsions qui maximisent la puissance transmise, en respectant le masque spectral de la FCC. Nous travaillons avec trois antennes et concevons une impulsion unique pour chacune d’entre elle. L’amélioration de l’énergie des impulsions UWB améliore directement la SNR au récepteur. Les résultats de simulation montrent que les impulsions optimisées améliorent considérablement le taux d’erreur (BER) par rapport au monocycle Gaussien sous propagation par trajet multiple. Notre autre contribution est l’évaluation d’un filtre adapté pour recevoir efficacement des impulsions UWB. Le filtre adapté est synthétisé et fabriqué en technologie microstrip, en collaboration avec l’Université McGill comme un dispositif de bande interdite électromagnétique. La réponse fréquentielle du filtre adapté montre une ex- cellente concordance avec le spectre ciblé de l’impulsion UWB. Les mesures de BER confirment la performance supérieure du filtre adapté par rapport à un récepteur à conversion directe. Le canal UWB est très riche en trajet multiple conduisant à l’ISI à haut débit. Notre dernière contribution est l’étude de performance des récepteurs en simulant un système avec des conditions de canaux réalistes. Les résultats de la simulation montrent que la performance d’un tel système se dégrade de façon significative pour les hauts débits. Afin de compenser la forte ISI dans les taux de transfert de données en Gb/s, nous étudions l’algorithme de Viterbi (VA) avec un nombre limité d’états et un égaliseur DFE (decision feedback equalizer). Nous examinons le nombre d’états requis dans le VA, et le nombre de coefficients du filtre dans le DFE pour une transmission fiable de UWB en Gb/s dans les canaux en ligne de vue. L’évaluation par simulation de BER confirme que l’égalisation améliore considérablement les performances par rapport à la détection de symbole. La DFE a une meilleure performance par rapport à la VA en utilisant une complexité comparable. La DFE peut couvrir une plus grande mémoire de canal avec un niveau de complexité relativement réduit.Ultra-wideband (UWB) communication has attracted an enormous amount of research in recent years, especially after the introduction of the US Federal Communications Commission (FCC) spectral mask. Ultra-short pulses allow for very high bit-rates while low power eliminates interference with existing narrowband systems. Low power, however, limits the propagation range of UWB radios to a few meters for indoors wireless transmission. Furthermore, received UWB signals are spread in time because of multipath propagation which results in high intersymbol interference at high data rates. Gaussian monocycle, the most commonly employed UWB pulse, has poor coverage under the FCC mask. In this thesis we demonstrate transmitters capable of generating UWB pulses with high power efficiency at Gb/s bit-rates. An efficient pulse results in higher signal-to-noise ratio (SNR) at the receiver by utilizing most of the available power under the FCC spectral mask. We generate the pulses in the optical domain and use optical fiber to transport the pulses over several kilometers for distribution in a passive optical network. Optical fiber is very reliable for transporting radio signals with low power consumption. We use simple elements such as a Mach Zehnder modulator or a ring resonator for pulse shaping, allowing for integration in silicon. Being compatible with CMOS technology, silicon photonics has huge potential for lowering the cost and bulkiness of optical systems. Photodetection converts the pulses to the electrical domain before antenna transmission at the user side. The frequency response of UWB antennas distorts the UWB waveforms. We pro- pose a nonlinear optimization technique which takes into account antenna distortion to find pulses that maximize the transmitted power, while respecting the FCC spectral mask. We consider three antennas and design a unique pulse for each. The energy improvement in UWB pulses directly improves the receiver SNR. Simulation results show that optimized pulses have a significant bit error rate (BER) performance improvement compared to the Gaussian monocycle under multipath propagation. Our other contribution is evaluating a matched filter to receive efficiently designed UWB pulses. The matched filter is synthesized and fabricated in microstrip technology in collaboration with McGill University as an electromagnetic bandgap device. The frequency response of the matched filter shows close agreement with the target UWB pulse spectrum. BER measurements confirm superior performance of the matched filter compared to a direct conversion receiver. The UWB channel is very rich in multipath leading to ISI at high bit rates. Our last contribution is investigating the performance of receivers by simulating a system employing realistic channel conditions. Simulation results show that the performance of such system degrades significantly for high data rates. To compensate the severe ISI at gigabit rates, we investigate the Viterbi algorithm (VA) with a limited number of states and the decision feedback equalizer (DFE). We examine the required number of states in the VA, and the number of taps in the DFE for reliable Gb/s UWB trans- mission for line-of-sight channels. Non-line-of-sight channels were also investigated at lower speeds. BER simulations confirm that equalization considerably improves the performance compared to symbol detection. The DFE results in better performance compared to the VA when using comparable complexity as the DFE can cover greater channel memory with a relatively low complexity level

An all-digital transmitter for pulsed ultra-wideband communication

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 91-96).Applications like sensor networks, medical monitoring, and asset tracking have led to a demand for energy-efficient and low-cost wireless transceivers. These types of applications typically require low effective data rates, thus providing an opportunity to employ simple modulation schemes and aggressive duty-cycling. Due to their inherently duty-cycled nature, pulse-based Ultra-Wideband (UWB) systems are amenable to low-power operation by shutting off circuitry during idle mode between pulses. Furthermore, the use of non-coherent UWB signaling greatly simplifies both transmitter and receiver implementations, offering additional energy savings. This thesis presents an all-digital transmitter designed for a non-coherent pulsed UWB system. By exploiting relaxed center frequency tolerances in non-coherent wideband communication, the transmitter synthesizes UWB pulses from an energy efficient, single-ended digital ring oscillator. Dual capacitively-coupled digital power amplifiers (PAs) are used in tandem to generate bipolar phase modulated pulses for spectral scrambling purposes. By maintaining opposite common modes at the output of these PAs during idle mode (i.e. when no pulses are being transmitted), low frequency turn-on and turn-off transients typically associated with single-ended digital circuits driving single-ended antennas are attenuated by up to 12dB. Furthermore, four level digital pulse shaping is employed to attenuate RF side lobes by up to 20dB. The resulting dual power amplifiers achieve FCC compliant operation in the 3.5, 4.0, and 4.5GHz IEEE 802.15.4a bands without the use of any off-chip filters or large passive components. The transmitter is fabricated in a 90nm CMOS process and requires a core area of 0.07mm2. The entirely digital architecture consumes zero static bias current, resulting in an energy efficiency of 17.5pJ/pulse at data rates up to 15.6Mbps.by Patrick Philip Mercier.S.M

A 64-Channel 965-μW Neural Recording SoC with UWB Wireless Transmission in 130-nm CMOS

This brief presents a 64-channel neural recording system-on-chip (SoC) with a 20-Mb/s wireless telemetry. Each channel of the analog front end consists of a low-noise bandpass amplifier, featuring a noise efficiency factor of 3.11 with an input-referred noise of 5.6 μVrms in a 0.001- to 10-kHz band and a 31.25-kSps 6-fJ/conversion-step 10-bit SAR analog-to-digital converter. The recorded signals are multiplexed in the digital domain and transmitted via an 11.7% efficiency pulse-position modulation ultrawideband transmitter, reaching a transmission range in excess of 7.5 m. The chip has been fabricated in a 130-nm CMOS process, measures 25 mm2, and dissipates 965 μW from a 0.5-V supply. This SoC features the lowest power per channel (15 μW) and the lowest energy per bit (48.2 pJ) among state-of-the-art wireless neural recording systems with a number of channels larger than 32. The proposed circuit is able to transmit the raw neural signal in a large bandwidth (up to 10 kHz) without performing any data compression or losing vital information, such as local field potentials

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

Ultra-Wideband Transceiver Design And Optimization

University of Minnesota Ph.D. dissertation. July 2015. Major: Electrical Engineering. Advisor: Ramesh Harjani. 1 computer file (PDF); xiii, 128 pages.The technology landscape has quickly changed over the last few years. Developments in personal area networks, IC technology, DSP processing and bio-medical devices have enabled the integration of short range communication into low cost personal health care solutions. Newer technologies and solutions are being developed to cater to the personal operating space(POS) and body area networks(BAN). Health care is driving towards using multiple sensor and therapeutic nodes inside the POS. Technology has enabled remote patient care where the patient has low cost on-body wearables that allow the patient/physician to access vital signs without the patient physically visiting the clinic. Big semiconductor giants want to move into the wearable health monitor space. Along with the developments in fitness based health wearables, there has been a lot of interest towards developing BAN devices catering to the 'mission-critical' wearables and implants. Hearing aids, EKG monitors, neurostimulators are some examples. This work explores the use of the 802.15 ulta wideband (UWB) standard for designing a radio to operate in the a wireless sensor network in the BAN. The specific application targeted is a hearing aid. However, the design in this work is capable of working in a low power low range application with the ability to have multiple data rates ranging from a few kHz to 10's of MHz. The first radio designed by Marconi using spark-gap transmitters was an impulse radio (IR). The IR UWB technology boasts of low power, low cost, high data rates, multiple channels, simultaneous networking, the ability to carry information through obstacles that more limited bandwidths cannot, and also potentially lower complexity hardware design. The inherent timing accuracy associated with the technology gives UWB transmissions immunity to multipath fading and are hence make them more suitable for a cluttered indoor environment. The key difference with the traditional narrowband transceiver is that instead of using continuous wave (CW) transmission, impulses in time are used. The timing accuracy associated with these impulses require synchronization in time, rather than synchronization in frequency for carrier-based CW systems. A complete fully integrated system is presented in thesis. This work presents a low-power noncoherent IR UWB transceiver operating at 5GHz in 0.13um CMOS. A fully-digital transmitter generates a shaped output pulse of 1GHz 3-dB bandwidth. DLLs provide a PVT-tolerant time-step resolution of 1ns over the entire symbol period and regulate the pulse generator center frequency. The transmitter outputs -31dBm (0.88pJ/pulse at 1Mpulse/s) with a dynamic (energy) efficiency of 16pJ/pulse. The transmit out pulse is FCC part 15 compliant over process voltage and temperature (PVT) variations. The transmitter is semi-compliant with IEEE 802.15.6 and IEEE 802.15.4 standards and will become completely compliant with minor modifications. The receiver presented in this work is a non-coherent energy detect IR UWB receiver. The receiver has an on-chip transformer preceding the LNA, which is followed by a super-regenerative amplifier (SRA), envelope detector, sample-and-holds, and a bank of comparators. The design is SRA based energy-detection receiver. Measured results show a receiver efficiency of 0.32nJ/bit at 20.8Mb/s and operation with inputs as low as -70dBm. The SRA based energy-detection receiver utilizes early/late detection for a two-step baseband synchronization algorithm. An integrated solution to the issue of synchronization is also proposed. The system proposed is capable of synchronization and tracking control. The system in this work utilizes early/late detection for a two-step baseband synchronization algorithm. The algorithm is implemented in Matlab and the time to synchronization is observed to be between 250us to a few couple of ms. Measurements have also been made using the receiver and manually implementing the algorithm. This work addresses all aspects time synchronization in an IR transceiver. The initial mismatch is addressed by two methods. Beyond the initial synchronization, the system presented in this system is also capable of tracking. This would mean that once the transceiver has been synchronized, the timing generation would continue to track the phase and the frequency changes depending upon crystal drift over time or movement between the receiver and the transmitter. A test was also performed on the complete transceiver system with two radios talking to each other over a highly attenuated wired channel

Ultra Low Power FM-UWB Transceiver for High-Density Wireless Sensor Networks

The WiseSkin project aims to provide a non-invasive solution for restoration of a natural sense of touch to persons using prosthetic limbs. By embedding sensor nodes into the silicone coating of the prosthesis, which acts as a sensory skin, WiseSkin targets to provide improved gripping, manipulation and mobility for amputees. Flexibility, freedom of movement and comfort demand unobtrusive, highly miniaturized, low-power sensing capabilities built into the artificial skin, which is then integrated with a sensory feedback system. Wireless communication between the sensor nodes provides more flexibility, better scalability and robustness compared to wired solution, and is therefore a preferred approach for WiseSkin. Design of an RF transceiver tailored for the specific needs of WiseSkin is the topic of this work. The properties of FM ultra-wide band (FM-UWB) modulation make it a good candidate for High-Density Wireless Sensor Networks (HD-WSN). The proposed FM-UWB receivers take advantage of short range to reduce power consumption, and exploit robustness of this wideband modulation scheme. The LNA, identified as the biggest consumer, is removed and signal is directly converted to dc, where amplification and demodulation are performed. Owing to 500 MHz bandwidth, frequency offset and phase noise can be tolerated, and a low-power, free-running ring oscillator can be used to generate the LO signal. The receiver is referred to as an approximate zero-IF receiver. Two receiver architectures are studied. The first one performs quadrature downconversion, and owing to the demodulator linearity, provides the multi-user capability. In the second receiver, quadrature demodulation is replaced by the single-ended one. Due to the nature of the demodulator, sensitivity degrades, and multiple FM-UWB signals cannot be resolved, but the consumption is almost halved compared to the first receiver. The proposed approach is verified through two integrations, both in a standard 65 nm bulk CMOS process. In the first run, a standalone quadrature receiver was integrated. Power consumption of 423 uW was measured, while achieving -70 dBm sensitivity. Good narrow-band interference rejection and multiuser capability with up to 4 FM-UWB channels could be achieved. In the second run, a full transceiver is integrated, with both quadrature and single-ended receivers and a transmitter, all sharing a single IO pad, without the need for any external passive components or switches. The quadrature receiver, with on-chip baseband processing and multi-user support, in this case consumes 550 uW, with a sesensitivity of -68 dBm. The low power receiver consumes 267 uW, and provides -57 dBm sensitivity, at a single FM-UWB channel. The implemented trantransmitter transmits a 100 kb/s FM-UWB signal at -11.4 dBm, while drawing 583 uW from the 1 V supply. The on-chip clock recovery allows reference frequency offset up to 8000 ppm. Since state of the art on-chip RC oscillators can provide below 2100 ppm across the temperature range of interest, the implemented transceiver demonstrates the feasibility of a fully integrated FM-UWB radio with no need for a quartz reference or any external components. In addition, the transceiver can tolerate up to 3 dBm narrow-band interferer at 2.4 GHz. Such a strong signal can be used to remotely power the sensor nodes inside the artificial skin and enable a truly wirelessWiseSkin solution

Advances in Integrated Circuit Design and Implementation for New Generation of Wireless Transceivers

User’s everyday outgrowing demand for high-data and high performance mobile devices pushes industry and researchers into more sophisticated systems to fulfill those expectations. Besides new modulation techniques and new system designs, significant improvement is required in the transceiver building blocks to handle higher data rates with reasonable power efficiency. In this research the challenges and solution to improve the performance of wireless communication transceivers is addressed. The building block that determines the efficiency and battery life of the entire mobile handset is the power amplifier. Modulations with large peak to average power ratio severely degrade efficiency in the conventional fixed-biased power amplifiers (PAs). To address this challenge, a novel PA is proposed with an adaptive load for the PA to improve efficiency. A nonlinearity cancellation technique is also proposed to improve linearity of the PA to satisfy the EVM and ACLR specifications. Ultra wide-band (UWB) systems are attractive due to their ability for high data rate, and low power consumption. In spite of the limitation assigned by the FCC, the coexistence of UWB and NB systems are still an unsolved challenge. One of the systems that is majorly affected by the UWB signal, is the 802.11a system (5 GHz Wi-Fi). A new analog solution is proposed to minimize the interference level caused by the impulse Radio UWB transmitter to nearby narrowband receivers. An efficient 400 Mpulse/s IR-UWB transmitter is implemented that generates an analog UWB pulse with in-band notch that covers the majority of the UWB spectrum. The challenge in receiver (RX) design is the over increasing out of blockers in applications such as cognitive and software defined radios, which are required to tolerate stronger out-of-band (OB) blockers. A novel RX is proposed with a shunt N-path high-Q filter at the LNA input to attenuate OB-blockers. To further improve the linearity, a novel baseband blocker filtering techniques is proposed. A new TIA has been designed to maintain the good linearity performance for blockers at large frequency offsets. As a result, a +22 dBm IIP3 with 3.5 dB NF is achieved. Another challenge in the RX design is the tough NF and linearity requirements for high performance systems such as carrier aggregation. To improve the NF, an extra gain stage is added after the LNA. An N-path high-Q band-pass filter is employed at the LNA output together with baseband blocker filtering technique to attenuate out-of-band blockers and improve the linearity. A noise-cancellation technique based on the frequency translation has been employed to improve the NF. As a result, a 1.8dB NF with +5 dBm IIP3 is achieved. In addition, a new approach has been proposed to reject out of band blockers in carrier aggregation scenarios. The proposed solution also provides carrier to carrier isolation compared to typical solution for carrier aggregation

Experimental Investigation Of Ultrawideband Wireless Systems: Waveform Generation, Propagation Estimation, And Dispersion Compensation

Ultrawideband (UWB) is an emerging technology for the future high-speed wireless communication systems. Although this technology offers several unique advantages like robustness to fading, large channel capacity and strong anti-jamming ability, there are a number of practical challenges which are topics of current research. One key challenge is the increased multipath dispersion which results because of the fine temporal resolution. The received response consists of different components, which have certain delays and attenuations due to the paths they took in their propagation from the transmitter to the receiver. Although such challenges have been investigated to some extent, they have not been fully explored in connection with sophisticated transmit beamforming techniques in realistic multipath environments. The work presented here spans three main aspects of UWB systems including waveform generation, propagation estimation, and dispersion compensation. We assess the accuracy of the measured impulse responses extracted from the spread spectrum channel sounding over a frequency band spanning 2-12 GHz. Based on the measured responses, different transmit beamforming techniques are investigated to achieve high-speed data transmission in rich multipath channels. We extend our work to multiple antenna systems and implement the first experimental test-bed to investigate practical challenges such as imperfect channel estimation or coherency between the multiple transmitters over the full UWB band. Finally, we introduce a new microwave photonic arbitrary waveform generation technique to demonstrate the first optical-wireless transmitter system for both characterizing channel dispersion and generating predistorted waveforms to achieve spatio-temporal focusing through the multipath channels