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Tuesday, May 10, 2011

Satellite, Wireless and Cellular Phones

          The tremendous success of satellite, wireless and cellular phones during the last several years has opened up the market for many other wireless systems like, e.g., wireless local area networks (WLANs), cordless phones, Bluetooth, etc. Several factors contributed to this success story. First, appropriate open standards for so-called second generation (2G) mobile communication systems have been developed, which guarantee interoperability of equipment from different manufacturers. Second, the needs of the users to communicate while on the move can perfectly be satisfied with 2G systems and additional services like short messaging services (SMS) turned out to become highly accepted. Third, the advances in silicon RF bipolar technology allowed building first radio frequency integrated circuits (RFIC) at the end of the 1980s. This made it possible to shrink mobile phones to acceptable form factors and increase the stand-by and talk-times to satisfying values. At the same time tremendous progress in deep sub-micrometer very large scale integration (VLSI) processing technology enabled the realization of digital IC's with powerful signal processing capabilities.
Today's mobile phones contain more than one million transistors, with only a small fraction operating in the RF range and the rest performing base band signal processing. Despite the by orders of magnitude higher complexity of the base band part, the RF front-end is still the design bottleneck of the entire system. One reason is that most of the current design environments have difficulties with the handling of the analog circuits which makes it impossible to perform system-level simulations to access tradeoffs and architectural decisions across the analog-digital boundary. Another reason for this design bottleneck is the fact that the design requires a thorough understanding of such diverse disciplines as communication theory, microwave theory, computer-aided design, multiple access, signal propagation, theory of random signals, wireless standards, and transceiver architectures, which are not directly related to IC design .
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