Silicon CMOS Technology is now the preferred process for low power wireless communication devices, although currently much noisier and slower than comparable processes such as SiGe Bipolar and GaAs technologies. However, due to ever-reducing gate sizes and correspondingly higher speeds, higher Ft CMOS processes are increasingly competitive, especially in low power wireless systems such as Bluetooth, Wireless USB, Wimax, Zigbee and W-CDMA transceivers. With the current 32 nm gate sized devices, speeds of 100 GHz and beyond are well within the horizon for CMOS technology, but at a reduced operational voltage, even with thicker gate oxides as compensation. This thesis investigates newer techniques, both from a systems point of view and at a circuit level, to implement an efficient transceiver design that will produce a more sensitive receiver, overcoming the noise disadvantage of using CMOS Silicon. As a starting point, the overall components and available SoC were investigated, together with their architecture. Two novel techniques were developed during this investigation. The first was a high compression point LNA design giving a lower overall systems noise figure for the receiver. The second was an innovative means of matching circuits with low Q components, which enabled the use of smaller inductors and reduced the attenuation loss of the components, the resulting smaller circuit die size leading to smaller and lower cost commercial radio equipment. Both these techniques have had patents filed by the University. Finally, the overall design was laid out for fabrication, taking into account package constraints and bond-wire effects and other parasitic EMC effects.

Abstract The focus of this thesis is on the binary signal detection problem, i.e., if a signal or signals are present or not. Depending on the application, the signal to be detected can be either unknown or known. The detection is based on some function of the received samples which is compared to a threshold. If the threshold is exceeded, it is decided that signal(s) is (are) present. Energy detectors (radiometers) are often used due to their simplicity and good performance. The main goal here is to develop and analyze energy based detectors as well as power-law based detectors. Different possibilities for setting the detection threshold for a quantized total power radiometer are analyzed. The main emphasis is on methods that use reference samples. In particular, the cell-averaging (CA) constant false alarm rate (CFAR) threshold setting method is analyzed. Numerical examples show that the CA strategy offers the desired false alarm probability, whereas a more conventional strategy gives too high values, especially with a small number of reference samples. New performance analysis of a frequency sweeping channelized radiometer is presented. The total power radiometer outputs from different frequencies are combined using logical-OR, sum and maximum operations. An efficient method is presented for accurately calculating the likelihood ratio used in the optimal detection. Also the effects of fading are analyzed. Numerical results show that although sweeping increases probability of intercept (POI), the final probability of detection is not increased if the number of observed hops is large. The performance of a channelized radiometer is studied when different CFAR strategies are used to set the detection threshold. The proposed iterative methods for setting the detection threshold are the forward consecutive mean excision (FCME) method with the CA scaling factors in final detection decision (FCME+CA), the backward consecutive mean excision (BCME) method with the CA scaling factors in detection (BCME+CA) and a method that uses the CA scaling factors for both censoring and detection (CA+CA). Numerical results show that iterative CFAR methods may improve detection performance compared to baseline methods. Finally, a method to set the threshold of a power-law detector that uses a nonorthogonal transform is presented. The mean, variance and skewness of the decision variable in the noise-only case are derived and these are used to find a shifted log-normal approximation for the distribution of the decision variable. The accuracy of this method is verified through simulations.

In the energy-limited wireless sensor node applications, wake-up radios are required to reduce the average power consumption of the node. Energy-detecting receivers are the best fit for such low power operations. This thesis presents the energy-detecting receiver design; challenges; techniques to enhance sensitivity, selectivity; and multi-access operation. Self-mixers instead of the conventional envelope detectors are proposed and proved to be optimal for signal detection. A fully integrated wake-up receiver uses the self-mixer and time-encoded baseband signal processing to provide a sensitivity of -79.1dBm at 434MHz with 420pW of power, providing an 8dB better sensitivity at 10dB lower power consumption compared to the SoA. A novel approach using narrowband interferers as local oscillators will be presented to further enhance sensitivity and selectivity, effectively operating the energy-detector receiver as a direct down-conversion receiver. Additionally, a clockless continuous-time analog correlator will be introduced to enhance the selectivity to wide-band AM interferers. The architecture uses pulse-position-encoded analog signal processing with VCOs as integrators and pulse-controlled relaxation delays; it operates as a code-domain matched filter to de-spread asynchronous wake-up codes. This code-domain matched filtering also provides code-division multiple access (CDMA) for simultaneous wakeups. Additional enhancement in the link can be achieved using directional antennas, providing spatial gain and selectivity. Certain applications can leverage a nearby reflector similar to a Yagi antenna to enhance the directivity. A low power directional backscatter tag is proposed, it uses multiple antennas acting as a reflectarray by configuring constant phase gradients depending on the direction of arrival (DoA) of the signal. Thus, instead of harvesting energy, the same energy and the surrounding environment can be leveraged to enhance functionality (e.g. interferer as LO, using a backscatter tag on a wall) for low power operation. Innovations spanning both system and circuit architectures that leverage the ambient energy and environment to enable power-efficient solutions for next-generation wake-up radios are presented in this work.

Millimetre-wave technology is used for applications such as telecommunications and imaging. For both applications, the bandwidth of existing systems has to be increased to support higher data rates and finer imaging resolutions. Millimetrewave circuits with very large bandwidths are developed in this thesis. The focus is put on amplifiers and the on-chip integration of the amplifiers with antennas. Circuit prototypes, fabricated in a commercially available 130nm Silicon-Germanium (SiGe) Bipolar Complementary Metal-Oxide-Semiconductor (BiCMOS) process, validated the developed techniques. Cutting-edge performances have been achieved in the field of distributed and resonant-matched amplifiers, as well as in that of the antenna-amplifier co-integration. Examples are as follows: - A novel cascode gain-cell with three transistors was conceived. By means of transconductance peaking towards high frequencies, the losses of the synthetic line can be compensated up to higher frequencies. The properties were analytically derived and explained. Experimental demonstration validated the technique by a Traveling-Wave Amplifier (TWA) able to produce 10 dB of gain over a frequency band of 170GHz.# - Two Cascaded Single-Stage Distributed Amplifiers (CSSDAs) have been demonstrated. The first CSSDA, optimized for low power consumption, requires less than 20mW to provide 10 dB of gain over a frequency band of 130 GHz. The second amplifier was designed for high-frequency operation and works up to 250 GHz leading to a record bandwidth for distributed amplifiers in SiGe technology. - The first complete CSSDA circuit analysis as function of all key parameters was presented. The typical degradation of the CSSDA output matching towards high frequencies was analytically quantified. A balanced architecture was then introduced to retain the frequency-response advantages of CSSDAs and yet ensure matching over the frequency band of interested. A circuit prototype validated experimentally the technique. - The first traveling-wave power combiner and divider capable of operation from the MHz range up to 200 GHz were demonstrated. The circuits improved the state of the art of the maximum frequency of operation and the bandwidth by a factor of five. - A resonant-matched balanced amplifier was demonstrated with a centre frequency of 185 GHz, 10 dB of gain and a 55GHz wide –3 dB-bandwidth. The power consumption of the amplifier is 16.8mW, one of the lowest for this circuit class, while the bandwidth is the broadest reported in literature for resonant-matched amplifiers in SiGe technology.

Background: Nowadays, the usage of social media starts at a very young age because of the availability of tools where social media platforms become available. Even though social media can be very usable in many cases, it can also be harmful. It can be seen that it is between the ages of 12-17 that teenage girls suffer the most from social media use as senders and receivers, and with this, there are negative effects that can harm these teenage girls. It is therefore important to understand the consequences that come when using social media as a teenage girl. Purpose: The purpose of this research is to explore how teenage girls, as senders and receivers, experience the negative effects of social media use. Method: This research undertook a qualitative research approach with an exploratory nature. In order for the researchers to collect data for the study a pilot test was first conducted in order to make sure that the actual semistructured interviews could be conducted. The semi-structured interviews were conducted by gathering data from participants of eight teenage girls between the ages of 12-17 from a local high school in Växjö, Sweden. Findings: This research found that the negative effects for a sender on social media were found to be sleep quality and the need to interact with others. Furthermore, the negative effects for a receiver were found to be sleep quality, the creation of bad habits, influencers, and undesired content. Conclusion: The findings show that there were more negative effects of using social media as a receiver than as a sender from the teenage girls perspective. Sleep quality was affecting both senders and receivers but in different aspects. The need to interact with others was the major impact on a sender on social media. Furthermore, the result showed that creation of bad habits, influencers, and undesired content were negatively affecting the teenage girls as receivers from their social media use.

Previous approach for narrowband interference cancellation based on compressed sensing (CS) in wideband receivers uses orthogonal projections to project away from the interference. This is not effective in the presence of nonlinear LNA (low noise amplifier) and finite bit ADCs (analog-to-digital converters) due to the fact that the nonidealities present will result in irresolvable intermodulation components and corrupt the signal reconstruction. Cancelling out the interferer before reaching the LNA thus becomes very important. A CS measurement matrix with randomly placed zeros in the frequency domain helps in this regard by removing the effect of interference when the signal measurements are performed before the LNA. Using this idea, under much idealized hardware assumptions impressive performance is obtained. The use of binary sequences which makes the hardware implementation simplistic is investigated in this thesis. Searching sequences with many spectral nulls turns out to be nontrivial. A theoretical approach for estimating probability of nulls is provided to reduce significant computational effort in the search and is shown to be close to actual search iterations. The use of real binary sequences (generated using ideal switches) obtained through the search does not do better compared to the orthogonal projection method in the presence of nonlinear LNA.

Ultra-wide Band (UWB) has sparked a lot of interest lately from the industry and academia. The growing capacity of the wireless industry is requires a new communication system that satisfies the high data rate which does not interfere with existing RF systems. UWB promises to be this new technology. UWB also promises low power, low cost and flexibility. The UWB Channel opens up a huge new wireless channel with Giga Hertz Capacities as well as the highest spatial capacities measured in bits per hertz per square meter. When properly implemented UWB channel can share spectrum with traditional radio systems without causing harmful interference. In this thesis we studied and compared several reduced complexity sub-optimal Ultra-Wide Band receivers. These receivers include auto correlation receiver, the square value detector and the absolute value detector are studied. We consider OOK and PPM modulation schemes. We examine these schemes and the receivers on Gaussian and UWB indoor channels. We compare the performance with optimal receivers. A transmitter receiver system using 0.1us pulses implemented using existing hardware. A packet consisting of 24 bits were transmitted and the received signal could be verified in real time using a vector signal analyzer. The results show sub-optimal receivers provide a better trade off between robust, complexity and performance.

Yes / A new generation of satellite systems that support regenerative on-board processors (OBPs) and multiple spot beam technology have opened new and efficient possibilities of implementing IP multicast communication over satellites. These new features have widened the scope of satellite-based applications and also enable satellite operators to efficiently utilize their allocated bandwidth resources. This makes it possible to provide cost effective satellite network services. IP multicast is a network layer protocol designed for group communication to save bandwidth resources and reduce processing overhead on the source side. The inherent broadcast nature of satellites, their global coverage (air, land, and sea), and direct access to a large number of subscribers imply satellites have unrivalled advantages in supporting IP multicast applications. IP mobility support in general and IP mobile multicast support in particular on mobile satellite terminals like the ones mounted on long haul flights, maritime vessels, continental trains, etc., still remain big challenges that have received very little attention from the research community. This paper proposes how Proxy Mobile IPv6 (PMIPv6)-based IP multicast mobility support defined for terrestrial networks can be adopted and used to support IP mobile multicast in future satellite networks, taking cognizance of the trend in the evolution of satellite communications.

Silicon CMOS Technology is now the preferred process for low power wireless communication devices, although currently much noisier and slower than comparable processes such as SiGe Bipolar and GaAs technologies. However, due to ever-reducing gate sizes and correspondingly higher speeds, higher Ft CMOS processes are increasingly competitive, especially in low power wireless systems such as Bluetooth, Wireless USB, Wimax, Zigbee and W-CDMA transceivers. With the current 32 nm gate sized devices, speeds of 100 GHz and beyond are well within the horizon for CMOS technology, but at a reduced operational voltage, even with thicker gate oxides as compensation. This thesis investigates newer techniques, both from a systems point of view and at a circuit level, to implement an efficient transceiver design that will produce a more sensitive receiver, overcoming the noise disadvantage of using CMOS Silicon. As a starting point, the overall components and available SoC were investigated, together with their architecture. Two novel techniques were developed during this investigation. The first was a high compression point LNA design giving a lower overall systems noise figure for the receiver. The second was an innovative means of matching circuits with low Q components, which enabled the use of smaller inductors and reduced the attenuation loss of the components, the resulting smaller circuit die size leading to smaller and lower cost commercial radio equipment. Both these techniques have had patents filed by the University. Finally, the overall design was laid out for fabrication, taking into account package constraints and bond-wire effects and other parasitic EMC effects.

Cognitive radio (CR) is a multi-disciplinary field that makes use of knowledge from a multitude of specialties such as antenna design, circuits, systems and digital signal processing among many others. CR has emerged as an area of interest over 20 years ago and in the years since has evolved to encompass both realizable theory and physical hardware. Key among the latter are reconfigurable, software defined radios and embedded sensors that incorporate flexible parameters, allowing a CR to operate in a wide variety of electromagnetic (EM) environments. The ideal cognitive radio would be capable of adapting to a changing EM environment without any specific knowledge or direction from the operator. This would require the radio itself to be aware of the EM environment and ideally, to sense the EM environment and act upon it in a semi-autonomous or autonomous way. While most research in this field has focused on the spectrum sensing aspects of the domain, development of the above-described "ideal CR" would require that the EM environment be characterized in domains such as angular, time and polarization among others. Signal dependent parameters can also be characterized such as bandwidth and modulation. The multi-dimensionality of the environment and the signals present within entail challenges with scalability and efficiency. This work focuses on the efficient sensing of signals in the angular domain also known as direction-of-arrival (DOA). There are a multitude of ways to find a signal's DOA. All require multiple antennas connected to a single or multiple radio nodes, antennas with patterns that gather energy in a particular direction, or multiple single antenna radios. The methods that utilize multiple antennas exploit the phase and/or amplitude relationships between the antennas themselves for a signal's DOA. The principal tradeoff between DOA methods typically converges to scan time vs. number of antenna elements. For many DOA architectures, this also means a scan time tradeoff with angular resolution as well. Since fast and accurate measurements are important for characterizing a quickly changing EM environment, sensing speed becomes a key requirement in designing a CR and associated sensing architecture. In this work, we present a DOA sensing architecture suitable for use in CR systems called the Direct Space to Information Converter (DSIC). Unlike current state-of-the art DOA methods, the DSIC breaks the tradeoff between scan time and the number of antenna elements needed for a given angular resolution when compared to other DOA and beamforming architectures. By randomly modulating the received signals in space, across multiple antenna elements and taking a few, compressed sensing (CS) measurements, the DSIC is able to angularly scan a wide field of view in an order of magnitude less time than other DOA methods. These CS measurements correspond to different random perturbations of the DSIC's antenna factor and can be quantized in as little as a single bit of resolution in the DSIC's phaseshifters/vector modulators. The DSIC is able to create multiple user-specified nulls in the antenna pattern to reduce the impact of strong known interferers while also simultaneously scanning the full field of view. Additionally, the designer has the option of performing simultaneous reception or nulling while sensing. If nulling, a few different methods are available each suitable for varying EM environments and potential use cases. We show in detail the multi-disciplinary process in designing a complete end-to-end hardware solution, selecting the parameters necessary to design the DSIC as well as test and characterize it. The benefits of the DSIC are discussed and compared to the current state-of the art with an emphasis on architectures suitable for use in interferer rich environments. We demonstrate that the energy usage of the DSIC is lower than comparable CR architectures by a large factor and scales much more favorably in terms of energy and physical complexity as the number of antenna elements increase. At the conclusion of this work we also discuss future areas of exploration in extending the DSIC's capability by incorporating an ability to sense the spectrum as well as the DOA of a signal.