Several Dsp Technology. Software Defined Radio

Software radio has emerged from obscurity to be heralded by some in the personal communications and other related industries as offering a potential solution to man抯 historical inability to achieve common global standards. It introduces the generality, flexibility and reconfigurability into the radio communication systems, and will make the interoperation among different systems better and help to easily upgrade the system. Although the advent of the true software-reconfigurable 搖niversal handset?may lie beyond the launch date of third-generation systems, the concepts of software radio will have profound impact on both technologies and industrial structures. This thesis first offers its concept and key techniques. As an important facet of its today implementation, the paper then illustrates some applications on base-band processing in WCDMA mobile communication systems (3GPP). These include modulation-demodulation, channel coding, filter designing and speech codec, etc. Finally, a software modem design and implementation are selected as an example. The aim is to extend software radio抯 idea in other communication fields. Chapters are arranged as following: Chapter 1 demonstrates system-level views and describes the whole framework of this paper. Chapter 2 discusses software radio抯 background, concepts, key techniques and potential applications. Chapter 3 provides implementation schemes of GMSK, QPSK modem and Turbo code. Turbo code, which has novel structures and amazing performance, ~vas believed to be mostly close to Shannon抯 Coding Theory. Data transmission over bandlimited channels requires pulse shaping to eliminate or control intersymbol interference (ISI). A shaping filter is needed, which fits Nyquist rule and can provide ISJ-free transmission. In Chapter 4, we discuss the design methods for this kind of filter in WCDMA applications and present our experiment results. VAD (Voice Activity Detection) is an important characteristic introduced by speech codec of mobile communications. Chapter 5 provides a design and implementation plan of VAD algorithm (AMR speech codec) in WCDMA systems. In fact, software radio抯 idea of flexibility and reconfigurability could also be introduced into other communication fields. Chapter 6 provides a further-explaining example, a special modem for Electric Power transmission. Appendices, which enumerate related experiment graphs and tables, provide some details for those interested in solving practical soft~vare radio-application problems in base-band signal processing using DSPs.