Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Software-Defined Radio—Basics and Evolution to Cognitive Radio | EURASIP Journal on Wireless Communications and Networking 2005 3 275-283 2005 Friedrich K. Jondral Software-Defined Radio Basics and Evolution to Cognitive Radio Friedrich K. Jondral Universitiit Karlsruhe TH Institutfur Nachrichtentechnik D-76128 Karlsruhe Germany Email fj@ Received 24 February 2005 Revised 4 April 2005 We provide a brief overview over the development of software-defined or reconfigurable radio systems. The need for software-defined radios is underlined and the most important notions used for such reconfigurable transceivers are thoroughly defined. The role of standards in radio development is emphasized and the usage of transmission mode parameters in the construction of software-defined radios is described. The software communications architecture is introduced as an example for a framework that allows an object-oriented development of software-defined radios. Cognitive radios are introduced as the next step in radio systems evolution. The need for cognitive radios is exemplified by a comparison of present and advanced spectrum management strategies. Keywords and phrases software-defined radio reconfigurable transceiver mobile communication standards cognitive radio advanced spectrum management. 1. INTRODUCTION Reconfigurability in radio development is not such a new technique as one might think. Already during the 1980s reconfigurable receivers were developed for radio intelligence in the short wave range. These receivers included interesting features like automatic recognition of the modulation mode of a received signal or bit stream analysis. Reconfigurability became familiar to many radio developers with the publication of the special issue on software radios of the IEEE Communication Magazine in April 1995. We refer to a transceiver as a software radio SR if its communication functions are realized as programs running on a suitable processor. Based on the same hardware different transmitter receiver algorithms which .
