Ultra-Wideband Pulse-Based Radio: Reliable Communication Over a Wideband Channel

ISBN-13: 9789048124497 / Angielski / Twarda / 2009 / 247 str.

Wim Vereecken; Michiel Steyaert

Opis

Today s booming expanse of personal wireless radio communications is a rich source of new challenges for the designer of the underlying enabling te- nologies. Personal communication networks are designed from a fundam- tally different perspective than broadcast service networks, such as radio and television. While the focus of the latter is on reliability and user comfort, the emphasis of personal communication devices is on throughput and mobility. However, because the wireless channel is a shared transmission medium with only very limited resources, a trade-off has to be made between mobility and the number of simultaneous users in a con?ned geographical area. Accord- 1 ing to Shannon s theorem on channel capacity, the overall data throughput of a communication channel bene?ts from either a linear increase of the tra- mission bandwidth, or an (equivalent) exponential increase in signal quality. Consequently, it is more bene?cial to think in terms of channel bandwidth than it is to pursue a high transmission power. All the above elements are embodied in the concept of spatial ef?ciency. By describing the throughput of a system 2 in terms of bits/s/Hz/m, spatial ef?ciency takes into account that the use of a low transmission power reduces the operational range of a radio transmission, and as such enables a higher reuse rate of the same frequency spectrum."

Spis treści

Contents. Preface. List of Abbreviations and Symbols. 1. DIGITAL COMMUNICATIONS OVER ANALOG CHANNELS. 1.1 Wideband radio: spectral and spatial efficiency. 1.2 Increasing the spectral bandwidth. 1.3 Onwards to software defined radio? 1.4 Interference immunity issues of wideband radio. 1.5 Organizational overview of this text. 2. MODULATION-AWARE ERROR CODING. 2.1 Why error coding works. 2.2 How error coding works. 2.3 Coding: the concept of distance. 2.4 Coding for a narrowband, noisy channel. 2.5 Coding and modulation for a wideband channel: OFDM. 2.6 Wideband single-carrier modulation. 2.7 Conclusions on single- and multicarrier systems. 3. MODULATION-AWARE DECODING: SIGNAL RECONSTRUCTION. 3.1 Principles of signal reconstruction. 3.2 ISSR decoding for wideband QPSK. 3.3 Implementation aspects of the ISSR algorithm. 3.4 Performance of the ISSR algorithm. 3.5 ISSR under non-ideal circumstances. 4. BENEFITS OF ISI IN THE INDOOR ENVIRONMENT. 4.1 Power delay spread. 4.2 Frequency-selective versus flat fading. 4.3 Coherence time. 4.4 Multipath resolvability and link reliability. 5. PULSE-BASED WIDEBAND RADIO. 5.1 Symbol rate versus multipath resolvability. 5.2 Synchronization. 5.3 ISSR-based diversity combining. 5.4 System integration and clock planning. 5.5 Overview of the pulse-based radio system. 6. REFERENCE DESIGN OF A PULSE-BASED RECEIVE UNIT. 6.1 Receive window specifications. 6.2 Multiphase clock generator. 6.3 RF input stage. 6.4 Design for testability. 6.5 Experimental results for the prototype chip. 6.6 Summary of the pulse-based receive unit. 6.7 Overview and future work. 7. NONLINEAR LOADED OPEN-LOOP AMPLIFIERS. 7.1 Interstage coupling of open-loop transistor stages. 7.2 Design considerations on the open-loop core stage. 7.3 Improving linearity using a nonlinear load. 7.4 Distortion analysis of the nonlinear loaded stage. 7.5 Sensitivity analysis of the open-loop amplifier. 7.6 Implementation of a linearized open-loop amplifier. 7.7 Overview and future work. Appendices. A. Distortion analysis of feedback amplifiers. References. Index.

Blurb

Today's booming expanse of personal wireless radio communications is a rich source of new challenges for the designer of the underlying enabling technologies. Because the wireless channel is a shared transmission medium with only very limited resources, a trade-off must be made between mobility and the number of simultaneous users in a confined geographical area.

Ultra-Wideband Pulse-based Radio lays the foundations of a new radio transceiver architecture, based on the Ultra-Wideband pulse-based radio principle. Instead of a continuous-time modulated carrier, the pulse-based radio system uses short electromagnetic pulses with a wide spectral footprint. This has considerable advantages for the reliability of a wireless link in an indoor environment. However, what is not accounted for in most high-level theoretical perspectives, is that a wide transmission bandwidth opens up a Pandora's box of many complications at receiver side. A real-world wireless channel, for example, suffers from multipath reflections: multiple, delayed versions of the same signal arrive at the receive antenna and start to interfere with one another, an effect that is known as intersymbol interference. Also, a wide transmission band is a wide open door for in-band interfering signals, caused by other transmitters in the same frequency band.

A specially crafted interferer suppression and signal reconstruction (ISSR) algorithm is presented in this book. Without active intervention from the transmitter, the ISSR algorithm is capable of on-the-fly cleaning of frequency bands which have fallen victim to multipath fading or narrowband interference. The unique blend of pulse-based radio, a simple modulation scheme and a powerful signal reconstruction system make the presented pulse-based radio system a very promising alternative for the high-end (but complex) OFDM-based modulation schemes currently used in many WLAN applications.