Abstract:
Over the last two decade or so, we have witnessed a drastic increase in the demand for providing reliable high speed wireless communication links to support applications such as voice, video, e-mail, web browsing, to name a few. This is a challenging task, however, since transmission through a wireless link is prone to a number of impairments of which the most important are fading and interference. In addition, in wideband communications (i.e., at high data rates), the signal bandwidth is normally larger than the channel bandwidth and this gives rise to frequency selective fading which occurs due to multipath components.
If we look at the evolution of wireless communication, it is among one of the biggest success stories of last two decades not only from a scientific point of view, where the progress has been phenomenal, but also in terms of market size andimpact on society. In fact wireless communication permeates in every aspect of our lives. As the demand for such high data rate applications is increasing, demand for bandwidth and spectral availability are endless as the wireless systems continue to strive for ever higher data rates. Multiple access wireless communication is being deployed for both fixed and mobile applications. In fixed applications, the wireless networks provide voice or data for fixed subscribers. Mobile networks offering voice and data services can be divided in to two classes: high mobility, to serve high speed vehicle borne users, and low mobility, to serve pedestrian users.
The gradual evolution of wireless communication systems follows the quest for high data rates, measured in bits/sec (bps) and with a high spectral efficiency, measured in bps/Hz. The first mobile communication systems were analog and are today referred to as systems of the first generation (1G). In the beginning of 1990s, the first digital systems emerged, denoted as second generation (2G) systems, the most popular 2G system introduced was the Global System for Mobile communications (GSM), which operates in the 900MHz or the
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