Realizing mobile multimedia systems over emerging fourth-generation wireless technologies

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Includes bibliographical references (p. [161]-167) and index.by Pei-Jeng Kuo.M.Eng

Optimisation of Bluetooth wireless personal area networks

In recent years there has been a marked growth in the use of wireless cellular telephones, PCs and the Internet. This proliferation of information technology has hastened the advent of wireless networks which aim to increase the accessibility and reach of communications devices. Ambient Intelligence (Ami) is a vision of the future of computing in which all kinds of everyday objects will contain intelligence. To be effective, Ami requires Ubiquitous Computing and Communication, the latter being enabled by wireless networking. The IEEE's 802.11 task group has developed a series of radio based replacements for the familiar wired ethernet LAN. At the same time another IEEE standards task group, 802.15, together with a number of industry consortia, has introduced a new level of wireless networking based upon short range, ad-hoc connections. Currently, the most significant of these new Wireless Personal Area Network (WPAN) standards is Bluetooth, one of the first of the enabling technologies of Ami to be commercially available. Bluetooth operates in the internationally unlicensed Industrial, Scientific and Medical (ISM) band at 2.4 GHz. unfortunately, this spectrum is particularly crowded. It is also used by: WiFi (IEEE 802.11); a new WPAN standard called Zig- Bee; many types of simple devices such as garage door openers; and is polluted by unintentional radiators. The success of a radio specification for ubiquitous wireless communications is, therefore, dependant upon a robust tolerance to high levels of electromagnetic noise. This thesis addresses the optimisation of low power WPANs in this context, with particular reference to the physical layer radio specification of the Bluetooth system

"Development of wireless fire products”

The project was to develop a radio controlled door holder system as the first in a range of radio based products for Stephenson Gobin Eng Co. Ltd. Stephenson Gobin manufacture and market a wide range of electromechanical products, including retaining devices for fire doors and smoke vents. Typical installations are in hospitals, nursing homes, shopping centers, hotels or any building open to the public. The author discusses why a radio controlled door holder system is commercially and technically viable. Various wired and Wirefree door holder systems are evaluated on merits of safety and ease of installation. Stephenson Gobin developed a bi-stable latching door holding device which consumed no current in a state that was capable of holding a fire door open. This was due to a rotating magnetic slug assembly which only drew current to latch from one state to other. The device needed to be controlled wirelessly and possible methods of communication were assessed. Communicating using the license free radio frequency spectrum was selected due to the falling costs of radio components and the huge growth in the radio communication sector. The author developed and tested the hardware and software necessary to communicate with and actuate such a device

Digital implementation of ETSI OFDM symbol synchronizer based on sliding correlation

This thesis presents the design, implementation, verification and synthesis of a digital hardware, which performs OFDM symbol synchronization using short training symbols (STS) defined in European Telecommunications Standards Institute (ETSI) HiperLan/2 Physical Layer specifications. Designed ETSI OFDM Symbol Synchronizer IP was synthesized in CMOS 0.13mM technology using Virtual Silicon Technology (VST) Standard Cell Libraries. In this thesis, we first explain OFDM and OFDM systems in detail. Synchronization problems occurring in OFDM systems are classified and techniques used to overcome these problems are presented. Then a digital ETSI OFDM Symbol Synchronizer IP, which performs OFDM symbol synchronization task based on the correlation of the received symbols, is proposed. Proposed architecture has been designed using VHDL (VHSIC Hardware Description Language) in the implementation part of the thesis. Designed IP has been verified functionally first, then synthesized in CMOS 0.13mM technology. Gate-level verification has been also performed after synthesis of the IP. Like other communication systems, synchronization is a critical problem to be solved in OFDM systems. One of the arguments against OFDM is that it is highly sensitive to synchronization errors. Before an OFDM receiver can demodulate the subcarriers, it has to perform at least two synchronization tasks: First, it has to find out where the symbol boundaries are. Second, it has to estimate and correct the carrier frequency offset of the received signal and clock offset between transmitter and receiver because any offset introduces Inter-carrier interference (ICI) and Inter-symbol interference (ISI). This work aims to review OFDM and synchronization issues in OFDM systems and to design a digital symbol synchronizer hardware that performs the detection of OFDM symbols, which is the first synchronization task mentioned above. ETSI HiperLAN/2 standard has been used in this work as the reference for all parameters needed and used in the hardware implementation of ETSI OFDM Symbol Synchronizer. Although the needed sampling frequency of OFDM receiver is 20 MHz in the ETSI standards, the designed IP can be run up to 50 MHz. It can be easily adapted to any changes in the standard, such as the increase in speed. The generically designed ETSI OFDM STS Symbol Synchronizer IP can be integrated to other modules easily and used as part of the whole synchronizer block in ETSI OFDM receivers

Exploring the hot-carrier effect on the wireless transceivers

Phase noise can be regarded as the most severe cause of performance degradation in the wireless communication systems. The hot-carriers (HCs), found in the CMOS synchronization circuits, are the high-energy charge carriers that degrade the MOSFET devices’ performance by increasing the threshold voltage required to operate the MOSFETs. The HC effect manifests itself as the phase noise whose level increases with the continued MOSFET operation and such increases result in the performance degradation of the voltage-controlled oscillator (VCO) built on the MOSFETs. The HC effect is particularly evident in the short-channel MOSFET devices. In this dissertation, we analyze the wireless transceiver performances in the presence of the synchronization errors induced by the HC effect, for both single-carrier and multi-carrier communication systems. We derive the relationship between the corresponding system performances and the HC effect in terms of a crucial parameter, the MOSFET threshold voltage. We employ a new phase noise model for the wireless systems influenced by the HC effect, which is based on a new precise phase noise mask function. In addition, we analyze the impact of the phase noise arising from the HC effect on the single-carrier wireless systems in terms of the BER and the signal-to-interference-plus-noise ratio (SINR). We derive the exact BER expression and show the SINR degradation for the QPSK systems that suffer from the phase noise. We apply Monte Carlo simulations to verify our analysis. To study the HC effect thoroughly, we simplify the BER expression as a new asymptotical analysis as the signal-to-noise ratio approaches to infinity and obtain the lower bound of the achievable BER for the single-carrier wireless systems. For multi-carrier systems, we focus our discussions on the orthogonal frequency division multiplexing (OFDM) systems. According to our simulations, we show that the bit-error-rate (BER) evaluation for OFDM using our new phase noise model in the presence of the HCs can be very different up to three orders-of-magnitude from the existing models disregarding the HCs. We have also found that the ICI self-cancellation coding is very effective for combating the phase noise in the OFDM systems

Investigation of Millimetre Wave Generation by stimulated Brillouin scattering for Radio Over Fibre Applications

The rising demand for greater bandwidth and increased flexibility in modern telecommunication systems has lead to increased research activities in the field of Millimetre Wave-Photonics. The combination of an optical access network and the radio propagation of high data-rate signals provides a solution to meet these demands. Such structures are also known as Radio Over Fibre Systems. They implement the optical Millimetre Wave generation in a central station and the transmission of radio waves via a remote antenna unit to the radio cell. The expected data rate is very high, due to the fact that both the optical and the radio-link provide a large transmission bandwidth. This dissertation concerns the investigation of a new and simple method for the flexible generation of Millimetre Waves for application in Radio Over Fibre systems. The method is based on the heterodyne detection of two optical waves in a photo detector. By externally amplitude modulating the optical wave, different sidebands are generated. Two of these sidebands are selected and amplified by the non-linear effect of stimulated Brillouin scattering. As a gain medium, a standard single mode fibre is used. According to the theoretical investigation, very good carrier performances are possible with this method, and a computer simulation shows little degradation in the signals during their propagation in the system. The measured results are in strong agreement with the theoretical analysis. Experimental results show that the system can be fully utilised as a Radio Over Fibre system. The thesis is divided into five main parts: Introduction – Theory – Simulation – Experiment – Conclusion. In the Introduction, an overview of the current methods of Millimetre Wave Generation, Radio Over Fibre and the nonlinear effects of Brillouin scattering is given. In the theoretical section, a differential equation system which mathematically describes the system is derived and also solved numerically. With a proof of the concept set-up, the simulated results are compared with the experimental data. In the last section the work is conclude and future tasks are discus

60 GHz photonic millimeter-wave communication systems

Currently available copper-based Internet access technologies like xDSL and DOCSIS cover data transmission speeds in the range of some 10 Mb/s. With new applications, an increase in bandwidth demand up to the Gb/s-range is expected for the next years. Therefore, an evolution of access networks by gradual replacement of copper-based by fiber-optic infrastructure is presently ongoing. A similar development can be predicted for wireless access technology operating within the classical microwave range. Due to regulatory requirements and a lack of bandwidth alternatives need to be developed in the millimeter-wave band. In this regard, the frequency range around 60 GHz has a special importance due to a worldwide available unlicensed spectrum of several GHz of bandwidth. In this context, the integration of wireless networks in fiber-optic networks by the fiber-optic transport of the radio signal (radio-over-fiber, RoF) is of particular importance. Besides the low-loss optical transport of a 60 GHz radio signal RoF technology furthermore allows to shift complexity from base stations to a central office by a centralized provision of the millimeter-wave carrier. This work deals with the modeling, realization and characterization of 60 GHz RoF systems providing data rates within the multi-Gb/s range. On the theoretical side, a system model has been developed comprising relevant electrical and optical noise sources and the transmission properties of fiber-optic and wireless links as well. This allows for instance to make reliable predictions of the expected system performance in the run-up to RoF system planning and thus to identify optimization potential. Using innovative approaches and technologies, 12.5 Gb/s data transmission has been realized via fiber and wirelessly for the first time over technical relevant distances. Also, if compared to conventional RoF systems the dispersion-limited fiber-optic range has been multiplied. Another RoF system in the frame of this work aimed for an uncompressed HDTV transmission, for instance for video conferencing with high resolution (1080p) and extremely low latency (telemedicine). The wireless transmission of an uncompressed HDTV signal has been successfully demonstrated. Including the previously achieved results and experiences, the system complexity has been significantly reduced

Optimising BFWA networks

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