Low power rf transceivers

This thesis details the analysis and design of ultra-low power radio transceivers operating at microwave frequencies. Hybrid prototypes and Monolithic Microwave Integrated Circuits (MMICs) which achieve power consumptions of less than 1 mW and theoretical operating ranges of over 10 m are described. The motivation behind the design of circuits exhibiting ultra low power consumption and, in the case of the MMICs, small size is the emerging technology of Wireless Sensor Networks (WSN). WSNs consist of spatially distributed ‘nodes’ or ‘specks’ each with their own renewable energy source, one or more sensors, limited memory, processing capability and radio or optical link. The idea is that specks within a ‘speckzone’ cooperate and share computational resources to perform complex tasks such as monitoring fire hazards, radiation levels or for motion tracking. The radio section must be ultra low power e.g. sub 1 mW in order not to drain the limited battery capacity. The radio must also be small in size e.g. less than 5 x 5 mm so that the overall speck size is small. Also, the radio must still be able to operate over a range of at least a metre so as to allow radio contact between, for example, rooms or relatively distant specks. The unsuitability of conventional homodyne topologies to WSNs is discussed and more efficient methods of modulation (On-Off Keying) and demodulation (non-coherent) are presented. Furthermore, it is shown how Super-Regenerative Receivers (SRR) can be used to achieve relatively large output voltages for small input powers. This is important because baseband Op-Amps connected at the RF receiver output generally cannot amplify small signals at the input without the output being saturated in noise (10mV is the smallest measured input for 741 Op-Amp). Instrumentation amplifiers are used in this work as they can amplify signals below 1mV. The thesis details the analysis and design of basic RF building blocks: amplifiers, oscillators, switches and detectors. It also details how the circuits can be put together to make transceivers as well as describing various strategies to lower power consumption. In addition, novel techniques in both circuit and system design are presented which allow the power consumption of the radio to be reduced by as much as 97% whilst still retaining adequate performance. These techniques are based on duty cycling the transmitter and receiver and are possible because of the discontinuous nature of the On-Off Keying signal. In order to ease the sensitivity requirements of the baseband receive amplifier a design methodology for large output voltage receivers is presented. The designed receiver is measured to give a 5 mV output for an input power of -90 dBm and yet consumes less than 0.7 mW. There is also an appendix on the non linear modelling of the Glasgow University 50nm InP meta-morphic High Electron Mobility Transistor (50nm mHEMT) and one on the non linear modelling of a commercial Step Recovery diode (SRD). Models for the 50 nm mHEMT and the SRD are useful in the analysis, simulation and design of oscillators and pulse generators respectively

Wireless Orbiter Hang-Angle Inclinometer System

A document describes a system to reliably gather the hang-angle inclination of the orbiter. The system comprises a wireless handheld master station (which contains the main station software) and a wireless remote station (which contains the inclinometer sensors, the RF transceivers, and the remote station software). The remote station is designed to provide redundancy to the system. It includes two RF transceivers, two power-management boards, and four inclinometer sensors

Multipath Polyphase Circuits and their Application to RF Transceivers

Nonlinearity and time-variance in radio frequency (RF) circuits leads to unwanted harmonics and intermodulation products, e.g. in power amplifiers and mixers. This paper reviews a recently proposed multipath polyphase circuit technique which can cancel such harmonics and intermodulation products. This will be illustrated using a power upconverter IC as an example. The upconverter works from DC to 2.4 GHz, and the multipath polyphase technique cleans its spectrum up to the 17th harmonic, keeping unwanted spurious responses more than 40dB below the carrier. The technique can also be useful for other applications, and some possible applications will be discussed

An antenna switching based NOMA scheme for IEEE 802.15.4 concurrent transmission

This paper introduces a Non-Orthogonal Multiple Access (NOMA) scheme to support concurrent transmission of multiple IEEE 802.15.4 packets. Unlike collision avoidance Multiple Access Control (MAC), concurrent transmission supports Concurrent-MAC (C-MAC) where packet collision is allowed. The communication latency can be reduced by C-MAC because a user can transmit immediately without waiting for the completion of other users’ transmission. The big challenge of concurrent transmission is that error free demodulation of multiple collided packets hardly can be achieved due to severe Multiple Access Interference (MAI). To improve the demodulation performance with MAI presented, we introduce an architecture with multiple switching antennas sharing a single analog transceiver to capture spatial character of different users. Successive Interference Cancellation (SIC) algorithm is designed to separate collided packets by utilizing the spatial character. Simulation shows that at least five users can transmit concurrently to the SIC receiver equipped with eight antennas without sacrificing Packet Error Rate

High Speed CMOS VCO For Advanced Communications [TK7871.99.M99 C435 2003 f rb][Microfiche 7271].

Peningkatan keperluan bagi komunikasi tanpa wayar dalam suara dan data telah memotivasikan kerja-kerja untuk meningkatkan tahap intregrasi dalam pemancar-penerima berfrekuensi radio (RF) baru-baru ini. The fast growing demand of wireless communications for voice and data has driven recent efforts to dramatically increase the level of integration in RF transceivers

Mobile Communication Networks and Digital Television Broadcasting Systems in the Same Frequency Bands – Advanced Co-Existence Scenarios

The increasing demand for wireless multimedia services provided by modern communication systems with stable services is a key feature of advanced markets. On the other hand, these systems can many times operate in a neighboring or in the same frequency bands. Therefore, numerous unwanted co-existence scenarios can occur. The aim of this paper is to summarize our results which were achieved during exploration and measurement of the co-existences between still used and upcoming mobile networks (from GSM to LTE) and digital terrestrial television broadcasting (DVB) systems. For all of these measurements and their evaluation universal measurement testbed has been proposed and used. Results presented in this paper are a significant part of our activities in work package WP5 in the ENIAC JU project “Agile RF Transceivers and Front-Ends for Future Smart Multi-Standard Communications Applications (ARTEMOS)”

Massive MIMO in Real Propagation Environments: Do All Antennas Contribute Equally?

Massive MIMO can greatly increase both spectral and transmit-energy efficiency. This is achieved by allowing the number of antennas and RF chains to grow very large. However, the challenges include high system complexity and hardware energy consumption. Here we investigate the possibilities to reduce the required number of RF chains, by performing antenna selection. While this approach is not a very effective strategy for theoretical independent Rayleigh fading channels, a substantial reduction in the number of RF chains can be achieved for real massive MIMO channels, without significant performance loss. We evaluate antenna selection performance on measured channels at 2.6 GHz, using a linear and a cylindrical array, both having 128 elements. Sum-rate maximization is used as the criterion for antenna selection. A selection scheme based on convex optimization is nearly optimal and used as a benchmark. The achieved sum-rate is compared with that of a very simple scheme that selects the antennas with the highest received power. The power-based scheme gives performance close to the convex optimization scheme, for the measured channels. This observation indicates a potential for significant reductions of massive MIMO implementation complexity, by reducing the number of RF chains and performing antenna selection using simple algorithms.Comment: Submitted to IEEE Transactions on Communication

DC Power Line Communication (PLC) on 868 MHz and 2.4 GHz Wired RF Transceivers

Efficient management through monitoring of Li-ion batteries is critical to the progress of electro-mobility and energy storage globally, since the technology can be hazardous if pushed beyond its safety boundaries. Battery management systems (BMSs) are being actively improved to reduce size, weight, and cost while increasing their capabilities. Using power line communication, wireless monitoring, or hybrid data links are one of the most advanced research directions today. In this work, we propose the use of radio frequency (RF) transceivers as a communication unit that can deliver both wired and wireless services, through their superior analog and digital signal processing capability compared to PLC technology. To validate our approach computational simulation and empirical evaluation was conducted to examine the possibility of using RF transceivers on a direct current (DC) bus for wired BMS. A key advantage of this study is that it proposes a flexible and tested system for communication across a variety of network scenarios, where wireless data links over disrupted connections may be enabled by using this technology in short-range wired modes. This investigation demonstrates that the IEEE 802.15.4-compliant transceivers with operating frequencies of 868 MHz and 2.4 GHz can establish stable data links on a DC bus via capacitive coupling at high data rates