619 research outputs found

    Ultra-Wideband RF Transceive

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    Ultra-Wideband CMOS Transceiver Front-End for Bio-Medical Radar Sensing

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    Since the Federal Communication Commission released the unlicensed 3.1-10.6 GHz frequency band for commercial use in early 2002, the ultra wideband (UWB) has developed from an emerging technology into a mainstream research area. The UWB technology, which utilizes wide spectrum, opens a new era of possibility for practical applications in radar sensing, one of which is the human vital sign monitoring. The aim of this thesis is to study and research the possibility of a new generation humanrespiration monitoring sensor using UWB radar technology and to develop a new prototype of UWB radar sensor for system-on-chip solutions in CMOS technology. In this thesis, a lowpower Gaussian impulse UWB mono-static radar transceiver architecture is presented. The UWB Gaussian pulse transmitter and receiver are implemented and fabricated using 90nm CMOS technology. Since the energy of low order Gaussian pulse is mostly condensed at lower frequency, in order to transmit the pulse in a very efficient way, higher order Gaussian derivative pulses are desired as the baseband signal. This motivates the advancement of the design into UWB high-order pulse transmitter. Both the Gaussian impulse UWB transmitter and Gaussian higher-order impulse UWB transmitter take the low-power and high-speed advantage of digital circuit to generate different waveforms. The measurement results are analyzed and discussed. This thesis also presents a low-power UWB mono-static radar transceiver architecture exploiting the full benefit of UWB bandwidth in radar sensing applications. The transceiver includes a full UWB band transmitter, an UWB receiver front-end, and an on-chip diplexer. The non-coherent UWB transmitter generates pulse modulated baseband signals at different carrier frequencies within the designated 3-10 GHz band using a digitally controlled pulse generator. The test shows the proposed radar transceiver can detect the human respiration pattern within 50 cm distance. The applications of this UWB radar sensing solution in commercialized standard CMOS technology include constant breathing pattern monitoring for gated radiation therapy, realtime monitoring of patients, and any other breathing monitoring. The research paves the way to wireless technology integration with health care and bio-sensor network

    Radio-Communications Architectures

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    Wireless communications, i.e. radio-communications, are widely used for our different daily needs. Examples are numerous and standard names like BLUETOOTH, WiFI, WiMAX, UMTS, GSM and, more recently, LTE are well-known [Baudoin et al. 2007]. General applications in the RFID or UWB contexts are the subject of many papers. This chapter presents radio-frequency (RF) communication systems architecture for mobile, wireless local area networks (WLAN) and connectivity terminals. An important aspect of today's applications is the data rate increase, especially in connectivity standards like WiFI and WiMAX, because the user demands high Quality of Service (QoS). To increase the data rate we tend to use wideband or multi-standard architecture. The concept of software radio includes a self-reconfigurable radio link and is described here on its RF aspects. The term multi-radio is preferred. This chapter focuses on the transmitter, yet some considerations about the receiver are given. An important aspect of the architecture is that a transceiver is built with respect to the radio-communications signals. We classify them in section 2 by differentiating Continuous Wave (CW) and Impulse Radio (IR) systems. Section 3 is the technical background one has to consider for actual applications. Section 4 summarizes state-of-the-art high data rate architectures and the latest research in multi-radio systems. In section 5, IR architectures for Ultra Wide Band (UWB) systems complete this overview; we will also underline the coexistence and compatibility challenges between CW and IR systems

    Ultra-Wideband Secure Communications and Direct RF Sampling Transceivers

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    Larger wireless device bandwidth results in new capabilities in terms of higher data rates and security. The 5G evolution is focus on exploiting larger bandwidths for higher though-puts. Interference and co-existence issues can also be addressed by the larger bandwidth in the 5G and 6G evolution. This dissertation introduces of a novel Ultra-wideband (UWB) Code Division Multiple Access (CDMA) technique to exploit the largest bandwidth available in the upcoming wireless connectivity scenarios. The dissertation addresses interference immunity, secure communication at the physical layer and longer distance communication due to increased receiver sensitivity. The dissertation presents the design, workflow, simulations, hardware prototypes and experimental measurements to demonstrate the benefits of wideband Code-Division-Multiple-Access. Specifically, a description of each of the hardware and software stages is presented along with simulations of different scenarios using a test-bench and open-field measurements. The measurements provided experimental validation carried out to demonstrate the interference mitigation capabilities. In addition, Direct RF sampling techniques are employed to handle the larger bandwidth and avoid analog components. Additionally, a transmit and receive chain is designed and implemented at 28 GHz to provide a proof-of-concept for future 5G applications. The proposed wideband transceiver is also used to demonstrate higher accuracy direction finding, as much as 10 times improvement

    Timing and Carrier Synchronization in Wireless Communication Systems: A Survey and Classification of Research in the Last 5 Years

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    Timing and carrier synchronization is a fundamental requirement for any wireless communication system to work properly. Timing synchronization is the process by which a receiver node determines the correct instants of time at which to sample the incoming signal. Carrier synchronization is the process by which a receiver adapts the frequency and phase of its local carrier oscillator with those of the received signal. In this paper, we survey the literature over the last 5 years (2010–2014) and present a comprehensive literature review and classification of the recent research progress in achieving timing and carrier synchronization in single-input single-output (SISO), multiple-input multiple-output (MIMO), cooperative relaying, and multiuser/multicell interference networks. Considering both single-carrier and multi-carrier communication systems, we survey and categorize the timing and carrier synchronization techniques proposed for the different communication systems focusing on the system model assumptions for synchronization, the synchronization challenges, and the state-of-the-art synchronization solutions and their limitations. Finally, we envision some future research directions

    Radio channel characterisation and system-level modelling for ultra wideband body-centric wireless communications

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    PhDThe next generation of wireless communication is evolving towards user-centric networks, where constant and reliable connectivity and services are essential. Bodycentric wireless network (BCWN) is the most exciting and emerging 4G technology for short (1-5 m) and very short (below 1 m) range communication systems. It has got numerous applications including healthcare, entertainment, surveillance, emergency, sports and military. The major difference between the BCWN and conventional wireless systems is the radio channel over which the communication takes place. The human body is a hostile medium from the radio propagation perspective and it is therefore important to understand and characterise the effect of the human body on the antenna elements, the radio propagation channel parameters and hence the system performance. In addition, fading is another concern that affects the reliability and quality of the wireless link, which needs to be taken into account for a low cost and reliable wireless communication system for body-centric networks. The complex nature of the BCWN requires operating wireless devices to provide low power requirements, less complexity, low cost and compactness in size. Apart from these characteristics, scalable data rates and robust performance in most fading conditions and jamming environment, even at low signal to noise ratio (SNR) is needed. Ultra-wideband (UWB) technology is one of the most promising candidate for BCWN as it tends to fulfill most of these requirements. The thesis focuses on the characterisation of ultra wideband body-centric radio propagation channel using single and multiple antenna techniques. Apart from channel characterisation, system level modelling of potential UWB radio transceivers for body-centric wireless network is also proposed. Channel models with respect to large scale and delay analysis are derived from measured parameters. Results and analyses highlight the consequences of static and dynamic environments in addition to the antenna positions on the performance of body-centric wireless communication channels. Extensive measurement i campaigns are performed to analyse the significance of antenna diversity to combat the channel fading in body-centric wireless networks. Various diversity combining techniques are considered in this process. Measurement data are also used to predict the performance of potential UWB systems in the body-centric wireless networks. The study supports the significance of single and multiple antenna channel characterisation and modelling in producing suitable wireless systems for ultra low power body-centric wireless networks.University of Engineering and Technology Lahore Pakista

    Impulse radio ultra wideband over fiber techniques for broadband in-building network applications

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    In recent years, the demand for high bandwidth and mobility from the end users has been continuously growing. To satisfy this demand, broadband communication technologies that combined the benefit of both wired and wireless are considered as vital solutions. These hybrid optical wireless solutions enable multi-Gbit/s transmission as well as adequate flexibility in terms of mobility. Optical fiber is the ideal medium for such hybrid solution due its signal transparency and wide bandwidth. On the other hand, ultra wideband(UWB) radio over optical fiber technology is considered to be one of the key promising technologies for broadband communication and sensor network applications. The growing interest for UWB is mainly due to its numerous attractive features, such as low power spectral density, tolerance to multipath fading, low probability of interception, coexistence with other wireless services and capability of providing cost-effective > 1 Gb/s transmission. The main idea of UWB over fiber is to deliver UWB radio signals over optical channels, where the optical part serves as a backbone communication infrastructure to carry the UWB signal with a bandwidth of several GHz. This enables multiple novel applications such as: range extension of high speed wireless personal area networks (WPANs), low cost distributed antenna systems, secure and intelligent networks, or delivering broadband services to remote areas. In particular, this thesis deals with novel concepts on shaping and generation of IR-UWB pulses, theoretical and experimental demonstrations over different fiber types, routing of integrated wired/wireless IR-UWB services and effect of fiber types on ranging/localization of IR-UWB-over-fiber systems. Accordingly, this thesis investigates techniques for delivery of high data rate wireless services using impulse radio ultra wideband (IR-UWB) over fiber technology for both access and in-building network applications. To effectively utilize the emission mask imposed for UWB technologies by the Federal Communications Commission(FCC), novel pulse shaping techniques have been investigated and experimentally demonstrated. Comparison of the proposed pulses with conventional ones in terms of the compliance to the FCC-mask requirements, spectral power efficiencies and wireless coverage has been theoretically studied. Simple and efficient optical generation of the new pulse has been experimentally demonstrated. Furthermore, performance evaluation of 2 Gb/s transmission of IR-UWB over different types of fiber such as 25 km silica single-mode, 4.4 km silica multi-mode and 100 m plastic heavily-multi-mode fiber have been performed. To improve the functionalities of in-building networks for the delivery of wireless services; techniques that provide flexibility in terms of dynamic capacity allocation have been investigated. By employing wavelength conversion based on cross-gain modulation in optical semiconductor amplifiers(SOA), routing of three optical channels of IR-UWB over fiber system has been experimentally realized. To reduce the cost of the overall system and share the optical infrastructure, an integrated testbed for wired baseband data and wireless IR-UWB over 1 km SMF-28 fiber has been developed. Accordingly, 1.25 Gb/s wired baseband and 2 Gb/s wireless IR-UWB data have been successfully transmitted over the testbed. Furthermore, to improve the network flexibility, routing of both wired baseband and wireless signals has been demonstrated. Additionally, the ranging and localization capability of IR-UWB over fiber for in-door wireless picocells have been investigated. The effect of different fiber types (4 km SMF, 4.4 km GI-MMF and 100 m PF GI-POF) on the accuracy of the range estimation using time-of-arrival (ToA) ranging technique has been studied. A high accuracy in terms of cm level was achieved due to the combined effect of high bandwidth IR-UWB pulses, short reach fiber and low chromatic dispersion at 1300nm wavelength. Furthermore, ranging/ localization using IR-UWB over fiber system provides additional benefit of centralizing complex processing algorithms, simplifying radio access points, relaxing synchronization requirement, enabling energy-efficient and efficient traffic management networks. All the concepts, design and system experiments presented in this thesis underline the strong potential of IR-UWB for over optical fiber(silica and plastic) techniques for future smart, capacity and energy-efficient broadband in-building network applications

    A 0.18µm CMOS UWB wireless transceiver for medical sensing applications

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    Recently, there is a new trend of demand of a biomedical device that can continuously monitor patient’s vital life index such as heart rate variability (HRV) and respiration rate. This desired device would be compact, wearable, wireless, networkable and low-power to enable proactive home monitoring of vital signs. This device should have a radar sensor portion and a wireless communication link all integrated in one small set. The promising technology that can satisfy these requirements is the impulse radio based Ultra-wideband (IR-UWB) technology. Since Federal Communications Commission (FCC) released the 3.1GHz-10.6GHz frequency band for UWB applications in 2002 [1], IR-UWB has received significant attention for applications in target positioning and wireless communications. IR-UWB employs extremely narrow Gaussian monocycle pulses or any other forms of short RF pulses to represent information. In this project, an integrated wireless UWB transceiver for the 3.1GHz-10.6GHz IR-UWB medical sensor was developed in the 0.18µm CMOS technology. This UWB transceiver can be employed for both radar sensing and communication purposes. The transceiver applies the On-Off Keying (OOK) modulation scheme to transmit short Gaussian pulse signals. The transmitter output power level is adjustable. The fully integrated UWB transceiver occupies a core area of 0.752mm^2 and the total die area of 1.274mm^2 with the pad ring inserted. The transceiver was simulated with overall power consumption of 40mW for radar sensing. The receiver is very sensitive to weak signals with a sensitivity of -73.01dBm. The average power of a single pulse is 9.8µW. The pulses are not posing any harm to human tissues. The sensing resolution and the target positioning precision are presumably sufficient for heart movement detection purpose in medical applications. This transceiver can also be used for high speed wireless data communications. The data transmission rate of 200 Mbps was achieved with an overall power consumption of 57mW. A combination of sensing and communications can be used to build a low power sensor
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