Comparison of Possible Approaches for the Development of Low-Budget Spectrum Analyzers for Sensor Networks in the Range of 2.4-2.5 GHz

В статті приведені розробка, реалізація і дослідження роботи аналізаторів спектру, які можуть бути використанні у сенсорних мережах і системах інтернету речей. В якості робочого частотного діапазону вибраний ISM — 2,4–2,5 ГГц. На етапі вибору апаратного забезпечення проведений порівняльний аналіз існуючих доступних мікроконтролерів для аналізу спектру, вибір апаратних інтерфейсів, замовлення необхідних модулів і електричних компонентів, а також вхідних контроль. Підчас розробки реалізовано кілька варіантів аналізаторів спектру на базі мікроконтролера і мікрозбірки TI Chipcon СС2500 з USB-інтерфейсами, а також модулів Cypress CYWUSB6935 з LPT- і USB-інтерфейсами. На етапі розробки проведено розробку друкованої плати, її виготовлення, монтаж компонентів, програмування мікроконтролерів, перевірка роботоздатності збірки, внесення виправлень, під’єднання до персонального комп’ютера і збірка в корпусі. Також проведений аналіз існуючого програмного забезпечення для збору інформації про стан безпроводового ефіру. За результатами порівняльних дослідів різних збірок аналізаторів спектру отримані спектрограми для різних типів сигналів. За цими типовими спектрограмами проведений порівняльний аналіз роботи різних прототипів. Запропоновані підходи до побудови сенсорів на базі аналізаторів спектру дозволяють створювати малопотужні модулі для вбудовування в існуючі безпроводові інформаційні мережі підприємств для запобігання міжканальної інтерференції і забезпечення цілісності передавання даних. В результаті експериментів видно, що не всі існуючі модулі сильно відрізняються за характеристиками, а якість їх роботи напряму пов’язана з типом і якістю антени. В статті приведено принципові електричні схеми, перелік елементів, приклади друкованих плат, програматори, програмне забезпечення і прототипи.The article deals with the development, implementation and research of the spectrum analyzers that can be used in sensor networks and Internet systems of things. As an operating frequency range, 2.4–2.5 GHz ISM is selected. At the stage of hardware selection, a comparative analysis of existing available microcontrollers for the analysis of the spectrum, the choice of hardware interfaces, the ordering of the required modules and electrical components, as well as the input control is carried out. During development, several variants of spectrum analyzers on the basis of microcontroller and TI Chipcon СС2500 microcontrollers with USB interfaces, as well as Cypress CYWUSB6935 modules with LPT and USB interfaces, have been implemented. At the development stage, the development of the printed circuit board, its fabrication, component assembly, microcontroller programming, the verification of the assembly's robustness, making corrections, connecting to a personal computer and assembly in the case have been carried out. An analysis of existing software for collecting information on the state of the wireless broadcast is also conducted. According to the results of comparative experiments of various collections of spectrum analyzers, spectrographs for different types of signals were obtained. On these typical spectrographs a comparative analysis of the work of various prototypes was conducted. The offered approaches to building sensors on the basis of spectrum analyzers allow to create low-power modules for embedding in existing wireless information networks of enterprises for prevention of inter-channel interference and ensuring the integrity of data transmission. As a result of experiments, it is evident that not all existing modules are very different in characteristics, and the quality of their work is directly related to the type and quality of the antenna. The article gives the basic electric circuits, a list of elements, examples of PCBs, programmers, software and prototypes

Comparison of Possible Approaches for the Development of Low-Budget Spectrum Analyzers for Sensor Networks in the Range of 2.4-2.5 GHz

The article deals with the development, implementation and research of the spectrum analyzers that can be used in sensor networks and Internet systems of things. As an operating frequency range, 2.4-2.5 GHz ISM is selected. At the stage of hardware selection, a comparative analysis of existing available microcontrollers for the analysis of the spectrum, the choice of hardware interfaces, the ordering of the required modules and electrical components, as well as the input control is carried out. During development, several variants of spectrum analyzers on the basis of microcontroller and TI Chipcon CC2500 microcontrollers with USB interfaces, as well as Cypress CYWUSB6935 modules with LPT and USB interfaces, have been implemented. At the development stage, the development of the printed circuit board, its fabrication, component assembly, microcontroller programming, the verification of the assembly's robustness, making corrections, connecting to a personal computer and assembly in the case have been carried out. An analysis of existing software for collecting information on the state of the wireless broadcast is also conducted. According to the results of comparative experiments of various collections of spectrum analyzers, spectrographs for different types of signals were obtained. On these typical spectrographs a comparative analysis of the work of various prototypes was conducted. The offered approaches to building sensors on the basis of spectrum analyzers allow to create low-power modules for embedding in existing wireless information networks of enterprises for prevention of inter-channel interference and ensuring the integrity of data transmission.Comment: in Ukrainia

Approaches for the Development of Low-Budget Analyzers of the Spectrum Sensor Networks 2.4–2.5 GHz

In Ukraine, more and more new home and industrial networks are being built with full or partial use of wireless technologies. Over the past few years, such technologies have become the de facto standard. The number of networks is increasing because of their affordability and ease of use, the emergence of industrial roaming systems, a wide range of antenna equipment and permissions fixed at the legislative level. When designing a wireless network, it is not possible to anticipate all the nuances: re-reflection, shading, directionality of the antennas of the receivers, etc., so after the construction of a real system, you need to check it and reduce the impact of negative factors. Spectrum analyzers help solve this problem

Wireless device identification from a phase noise prospective

As wireless devices become increasingly pervasive and essential, they are becoming both a target for attacks and the very weapon with which such an attack can be carried out. Wireless networks have to face new kinds of intrusion that had not been considered previously because they are linked to the open nature of wireless networks. In particular, device identity management and intrusion detection are two of the most significant challenges in any network security solution but they are paramount for any wireless local area networks (WLANs) because of the inherent non-exclusivity of the transmission medium. The physical layer of 802.11-based wireless communication does not offer security guarantee because any electromagnetic signal transmitted can be monitored, captured, and analyzed by any sufficiently motivated and equipped adversary within the 802.11 device's transmission range. What is required is a form of identification that is nonmalleable (cannot be spoofed easily). For this reason we have decided to focus on physical characteristics of the network interface card (NIC) to distinguish between different wireless users because it can provide an additional layer of security. The unique properties of the wireless medium are extremely useful to get an additional set of information that can be used to extend and enhance traditional security mechanisms. This approach is commonly referred to as radio frequency fingerprinting (RFF), i.e., determining specific characteristics (fingerprint) of a network device component. More precisely, our main goal is to prove the feasibility of exploiting phase noise in oscillators for fingerprinting design and overcome existing limitations of conventional approaches. The intuition behind our design is that the autonomous nature of oscillators among noisy physical systems makes them unique in their response to perturbations and none of the previous work has ever tried to take advantage of thi

In Situ Measurement and Emulation of Severe Mulitipath Environments

ABSTRACT For a variety of wireless sensor network applications, sensor nodes may find their received signal strengths dominated by small-scale propagation effects. Particularly impacted are applications designed to monitor structural health and environmental conditions in metal cavities such as aircraft, busses, and shipping containers. Small changes in each sensor’s position or carrier frequency can cause large variations in this received signal strength, thereby compromising link connectivity. We leverage a technique called Wireless Sensors Sensing Wireless (WSSW) in which wireless sensors act as scalar network analyzers in order to characterize their own environment. WSSW data can enable sensors to react to particularly bad fading, such as hyper-Rayleigh, by switching to a good channel or by implementing other mitigation techniques, such as utilizing a diversity antenna. In this work, the WSSW concept has been extended to accommodate mesh networks and include a spectrum analysis capability for recognizing potentially interfering wireless activity. The test of mitigation techniques is often problematic since application sites are far from controlled environments and are often difficult to access. To address this problem, we have developed a Compact Reconfigurable Channel Emulator (CRCE) to create a laboratory environment that is configurable to a variety of repeatable fading scenarios. With the CRCE, fading characteristics found at a specific wireless sensor network location may be replicated inside the chamber to discover the connectivity capabilities of the sensors and the effectiveness of diversity schemes (e.g., channel switching or multi-element antenna arrays)

New Radio Small Cell Propagation Environment

The characterization of the wireless medium in indoor small cell networks is essential to obtain appropriate modelling of the propagation environment. This dissertation on ”MeasurementBased Characterization of the 5G New Radio Small Cell Propagation Environment” has been developed in an experimental environment. The underlying tasks are divided into three phases. The first phase took place in the laboratory of the Instituto de Telecomunicações – Covilhã, located in the Departamento de Engenharia Electromecânica of Universidade da Beira Interior. During this part of the research, spectrum measurements and the characterization of the S11 parameter (response in the first port for the signal incident in the first port) have been made experimentally through the printed circuit board antennas in the 2.6 GHz and 3.5 GHz frequency bands operating in the 2.625 GHz and 3.590 GHz center frequency, manufactured by us. The fabrication of the antennas was preceded by the simulation in the student version CST STUDIO software. In this phase, the spectrum measurements and the characterization of Smith Chart have been made to measure gain and impedance using the Rohde & Schwarz Vector Network Analyzer (VNA) from IT laboratory. Based on mathematical calculations and considerations on the conductivity and permeability of the environment, the antennas were built for use in indoor and outdoor environments. The developed antennas are characterized by their bandwidth and their radiation characteristics. The second phase took place in the three rooms adjacent to the laboratory, in which the srsLTE emulation software was applied to the 4G indoor scenario. The experimental setup includes three elements, namely a base station (BS or 4G eNodeB), which transmits the communication signal and which served as a signal source, a user equipment (UE), and an interfering eNodeB. The size of each room is 7.32 × 7.32 square meters. While room 1 is the room of interest, where theoretical and practical measurements took place, BSs that act as wireless interfering nodes are also separately considered either in room 2 or room 3. By varying the UE positions within room 1, it was possible to verify that the highest values of the received power occur close to the central BS. However, the received power does not decrease suddenly because of the reduced gain in the radiation pattern in the back part of the antenna. In addition, it was demonstrated that there is an effect of “wall loss”proven by the path loss increase between room 1 and room 2 (or between room 2 and 3). If we consider an attenuation for each wall of circa 7-9 dB the trend of the WINNER II at 2.625 GHz model for the interference coming across different walls is verified. Future work includes to investigate the 3.5 GHz frequency band. The third phase is being carried out at the facilities of the old aerodrome of Covilhã which, using a temporary license assigned to us by Instituto de Comunicações Português (ICP-ANACOM) as the two first phases. The aim of this phase is to investigate the two-slope behaviour in the UMi scenario. Very initial LTE-Advanced tests have been performed to verify the propagation of the two ray (with a reflection in the asphalt) from BS implemented with USRP B210 and srsLTE system by considering an urban cell with a length of 80 m and an interfering base station at 320 m, at 2500 - 2510 MHz (DL - Downlink) by now, mainly due to the current availability of a directional antenna in this specific band.A investigação de sinais rádio em comunicações sem fios continua a gerar considerável interesse em todo mundo, devido ao seu amplo leque de aplicações, que inclui a troca de dados entre dois ou mais dispositivos, comunicações móveis e via Wi-Fi, infravermelho, transmissão de canais de televisão, monitorização de campos, proteção e vigilância costeira e observação ambiental para exploração. A tecnologia de ondas de rádio é o um dos vários recursos que viabilizam as comunicações de alta velocidade e encurta distâncias entre dois pontos em comunicação. Na realidade, caracterização da comunicação em redes com pequenas células é essencial para obter uma modelização apropriada de ambiente de propagação. Esta dissertação sob o tema ”Measurement-Based Characterization of the 5G New Radio Small Cells Propagation Envioronment” foi desenvolvida num ambiente experimental, cujas tarefas foram divididas em fases. A primeira fase teve lugar no laboratório do Instituto de Telecomunicações da Covilhã (IT), afeto ao Departamento de Engenharia Eletromecânica. Nela foram feitas as simulações das antenas no software CST STUDIO, versão do estudante que foram utilizadas nos equipamentos durante as medições. Seguiu-se a padronização das mesmas nas faixas dos 2.6 GHz e 3.5 GHz, nas frequências centrais de 2.625 GHz e 3.590 GHZ, usando placas de circuitos impressos. Em seguida, foram feitas as medições do espectro e a caraterização do S11 e da carta de Smith para medir a impedância de entrada e o ganho. As medições foram feitas com recurso ao Vector Network Analyzer (VNA). Com base em cálculos matemáticos e considerações sobre a condutividade e permeabilidade do ambiente, as antenas foram construídas para uso em ambientes internos e externos e com ou sem interferentes. As antenas desenvolvidas são caracterizadas por sua largura de banda e suas características de radiação. A segunda fase decorreu nas três salas adjacentes ao laboratório de Telecomunicações, na qual foi montada a topologia com o sistema srsLTE associado aos USRP B210 ligados aos computadores com o sistema operativo Linux com três componentes, nomeadamente uma estação base (BS), que serviu de fonte do sinal de comunicação com um equipamento de utilizador (UE) que o recebe, e dois interferentes. Importa realçar que esta segunda fase foi dividida em duas etapas, das quais uma sem interferente para medir a potência recebida da própria estação base e outra com os interferentes mais próximo e mais afastado da sala do sinal da própria célula. O objetivo desta fase foi o de verificar o modelo de propagação do sinal de comunicação da tecnologia LTE e medir a potência recebida pelo utilizador com recurso ao Analisador de Espectro portátil FSH8 da Rohde & Schwarz capaz de medir de 10 kHz a 8 GHz, feita na frequência central de 2.625 GHz. Nas medições feitas em ambiente interior, o tamanho de cada uma das três salas é 7.32 × 7.32 metros quadrados. Embora a sala 1 seja a sala de interesse, onde ocorreram as medições teóricas e práticas, as BSs que atuam como nós interferentes também são consideradas separadamente na sala 2 ou na sala 3. Ao variar as posições de UE dentro da sala 1, foi possível verificar que os valores superiores da potência recebida ocorrem próximos à BS central. No entanto, a potência recebida não diminui repentinamente por causa do efeito do ganho reduzido no diagrama de radiação na parte traseira da antena. Além disso, foi demonstrado que existe um efeito de “atenuação da parede” comprovado pelo aumento da atenuação de trajeto entre a sala 1 e a sala 2 (ou entre a sala 2 e 3). Se considerarmos uma atenuação para cada parede de cerca de 7-9 dB, verifica-se a tendência do modelo WINNER II a 2.625 GHz para a interferência que atravessa as diversas paredes. Trabalhos futuros incluem a investigação da banda de frequência de 3.5 GHz. Já a terceira fase foi realizada nas instalações do antigo aeródromo da Covilhã, e em todas as fases servimo-nos de uma licença concedida pela Entidade Reguladora do Espectro (ICPANACOM), que permitiu realizar testes de verificação da propagação do sinal no ambiente livre na faixa de frequência dos 2.6 GHz com 2500 – 2510 MHz (UL - Uplink) e 2620 – 2630 MHz (DL - Downlink). A terceira fase ainda está a decorrer nas instalações do antigo aeródromo da Covilhã, mediante a mesma licença temporária que nos foi atribuída pelo Instituto de Comunicações de Portugal ou Autoridade Nacional de Comunicações (ICP-ANACOM) sendo esta reguladora do espectro. O objetivo é continuar a investigar o comportamento de duas inclinações no cenário UMi. Testes muito iniciais LTE-Advanced foram realizados para verificar a propagação dos dois raios (direto e refletido, com uma reflexão no asfalto) do BS implementado com o sistema USRP B210 e srsLTE, considerando uma célula urbana com um comprimento de 80 metros uma estação base interferente em 320 metros, a operar, provisoriamente, a 2500 - 2510 MHz (na ligação descendente, DL - Downlink, devido à disponibilidade de uma antena direcional específica para esta banda). Finalmente este trabalho de investigação pode ser resumidamente dividido em três categorias, nomeadamente investigação de análises teóricas e matemáticas relevantes da propagação de ondas de rádio em meios com e sem interferência significativa. Medições para verificar o comportamento do sinal de propagação da tecnologia LTE-Advanced com recursos ao analisador de espectro, simulação das antenas, fabricação e medição das características de radiação das mesmas. Assim, as antenas concebidas com bons resultados foram fabricadas nas instalações da Faculdade de Ciências no Departamento de Física da Universidade da Beira Interior, sendo de seguidas testadas e caracterizadas com o auxílio do Vector Nettwork Analyzer disponível no Laboratório de Telecomunicações do Departamento de Engenharia Eletromecânica da Universidade da Beira Interior. E, finalmente, os cálculos estatísticos que incluem o teste de normalidade de Kolmogorov-Smirnov com recurso ao software estatístico SPSS para validar os resultados obtidos seguida da construção dos gráficos no Matlab em 3D, conforme a superfície da sala

Performance Evaluation of Connectivity and Capacity of Dynamic Spectrum Access Networks

Recent measurements on radio spectrum usage have revealed the abundance of under- utilized bands of spectrum that belong to licensed users. This necessitated the paradigm shift from static to dynamic spectrum access (DSA) where secondary networks utilize unused spectrum holes in the licensed bands without causing interference to the licensed user. However, wide scale deployment of these networks have been hindered due to lack of knowledge of expected performance in realistic environments and lack of cost-effective solutions for implementing spectrum database systems. In this dissertation, we address some of the fundamental challenges on how to improve the performance of DSA networks in terms of connectivity and capacity. Apart from showing performance gains via simulation experiments, we designed, implemented, and deployed testbeds that achieve economics of scale. We start by introducing network connectivity models and show that the well-established disk model does not hold true for interference-limited networks. Thus, we characterize connectivity based on signal to interference and noise ratio (SINR) and show that not all the deployed secondary nodes necessarily contribute towards the network\u27s connectivity. We identify such nodes and show that even-though a node might be communication-visible it can still be connectivity-invisible. The invisibility of such nodes is modeled using the concept of Poisson thinning. The connectivity-visible nodes are combined with the coverage shrinkage to develop the concept of effective density which is used to characterize the con- nectivity. Further, we propose three techniques for connectivity maximization. We also show how traditional flooding techniques are not applicable under the SINR model and analyze the underlying causes for that. Moreover, we propose a modified version of probabilistic flooding that uses lower message overhead while accounting for the node outreach and in- terference. Next, we analyze the connectivity of multi-channel distributed networks and show how the invisibility that arises among the secondary nodes results in thinning which we characterize as channel abundance. We also capture the thinning that occurs due to the nodes\u27 interference. We study the effects of interference and channel abundance using Poisson thinning on the formation of a communication link between two nodes and also on the overall connectivity of the secondary network. As for the capacity, we derive the bounds on the maximum achievable capacity of a randomly deployed secondary network with finite number of nodes in the presence of primary users since finding the exact capacity involves solving an optimization problem that shows in-scalability both in time and search space dimensionality. We speed up the optimization by reducing the optimizer\u27s search space. Next, we characterize the QoS that secondary users can expect. We do so by using vector quantization to partition the QoS space into finite number of regions each of which is represented by one QoS index. We argue that any operating condition of the system can be mapped to one of the pre-computed QoS indices using a simple look-up in Olog (N) time thus avoiding any cumbersome computation for QoS evaluation. We implement the QoS space on an 8-bit microcontroller and show how the mathematically intensive operations can be computed in a shorter time. To demonstrate that there could be low cost solutions that scale, we present and implement an architecture that enables dynamic spectrum access for any type of network ranging from IoT to cellular. The three main components of this architecture are the RSSI sensing network, the DSA server, and the service engine. We use the concept of modular design in these components which allows transparency between them, scalability, and ease of maintenance and upgrade in a plug-n-play manner, without requiring any changes to the other components. Moreover, we provide a blueprint on how to use off-the-shelf commercially available software configurable RF chips to build low cost spectrum sensors. Using testbed experiments, we demonstrate the efficiency of the proposed architecture by comparing its performance to that of a legacy system. We show the benefits in terms of resilience to jamming, channel relinquishment on primary arrival, and best channel determination and allocation. We also show the performance gains in terms of frame error rater and spectral efficiency

Doctor of Philosophy

dissertationThe wireless radio channel is typically thought of as a means to move information from transmitter to receiver, but the radio channel can also be used to detect changes in the environment of the radio link. This dissertation is focused on the measurements we can make at the physical layer of wireless networks, and how we can use those measurements to obtain information about the locations of transceivers and people. The first contribution of this work is the development and testing of an open source, 802.11b sounder and receiver, which is capable of decoding packets and using them to estimate the channel impulse response (CIR) of a radio link at a fraction of the cost of traditional channel sounders. This receiver improves on previous implementations by performing optimized matched filtering on the field-programmable gate array (FPGA) of the Universal Software Radio Peripheral (USRP), allowing it to operate at full bandwidth. The second contribution of this work is an extensive experimental evaluation of a technology called location distinction, i.e., the ability to identify changes in radio transceiver position, via CIR measurements. Previous location distinction work has focused on single-input single-output (SISO) radio links. We extend this work to the context of multiple-input multiple-output (MIMO) radio links, and study system design trade-offs which affect the performance of MIMO location distinction. The third contribution of this work introduces the "exploiting radio windows" (ERW) attack, in which an attacker outside of a building surreptitiously uses the transmissions of an otherwise secure wireless network inside of the building to infer location information about people inside the building. This is possible because of the relative transparency of external walls to radio transmissions. The final contribution of this dissertation is a feasibility study for building a rapidly deployable radio tomographic (RTI) imaging system for special operations forces (SOF). We show that it is possible to obtain valuable tracking information using as few as 10 radios over a single floor of a typical suburban home, even without precise radio location measurements

Interrogation of Optical Fiber Sensors for Civil Engineering Applications using Widely Tunable Laser

Předložená disertační práce zkoumá možnosti použití nového typu polovodičového MGY- Laseru elektricky laditelného v širokém spektrálním rozsahu a zabývá se možnostmi jeho nasazení v optovláknové senzorové síti založené na metodě FBG (Fiber Bragg Grating). Výzkum byl započat komplexními dlouhodobými testy reálného měřícího scénáře z oblasti stavebnictví, sestaveného pro účely ověření limitujících aspektů současných technik. Inženýrské aplikace nabízejí velké množství vzájemně se vylučujících požadavků pro návrh strukturálních senzorových systémů. Tyto požadavky jsou sdíleny mnoha dalšími technologickými oblastmi, což přispívá k vysokému stupni univerzálnosti použití dosažených výsledků. Na základě posouzení stavu současné techniky a aplikačních požadavků byly v práci nejprve identifikovány aspekty, které mají být výzkumem zlepšeny. V dalším kroku byl detailně charakterizován MG-Y laser Syntune/Finisar S7500. Na základě dat získaných měřením byla zkoumána nová metoda spojitého řízená vlnové délky záření laseru. Provedené experimenty vedly nejen k návrhu nového způsobu spojité regulace vlnové délky ale také k vytvoření prostředků pro vlastní kalibraci systému na základě jeho vnitřních vlastností (podélných módů rezonátoru).This dissertation investigates the use of a MG-Y-Laser, a novel type of semiconductor laser that is electrically tunable over a wide spectral range, for the interrogation of Fiber Bragg Grating (FBG) based fiber-optical sensing networks. The research started with a complex long-term test of a real world measurement scenario from the field of civil engineering to elucidate limiting aspects of state of the art techniques. Civil engineering applications pose a multitude of mutually exclusive challenges toward structural sensing systems. These challenges are shared by many other fields of technology, making the results to a large degree universally applicable. Following an assessment of the state of art and the application requirements, the aspects to be improved by the research were identified. A Syntune/Finisar S7500 MG-Y-Laser device was then thoroughly characterized. Based on the gathered measurement data, novel tuning methods aimed at wavelength continuous control were investigated. This led to the invention of a tuning method that not only allows wavelength continuous control but also provides a means of self calibration based on intrinsic properties (longitudinal cavity modes) of the device.

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